Method and an apparatus for encoding video data for seamless connection using flags to indicate top or bottom of field and whether a field is presented plural times

ABSTRACT

A signal conversion recording method applies a signal recording method whereby a video signal converted to a frame rate greater than the frame rate of the signal source by repeating particular fields plural times is converted to an intermediate signal having a frame rate substantially equal to the frame rate of the original signal source by deleting these repeated redundant fields. This intermediate signal is compression coded to obtain the recording signal, and the recording signal is recorded to a recording medium together with a repeat first field flag RFF declaring whether a field was deleted, and a top field first flag TFF declaring which of the two fields in the each of the resulting frames is first on the time-base, is wherein when plural logical recording periods are provided on a single recording medium, the video signal is converted to the recording signal so that the flags hold particular values at the start and end of each recording period.

This application is a division of application Ser. No. 08/724,231, filedSep. 27, 1996, now U.S. Pat. No. 5,745,645.

BACKGROUND OF THE INVENTION

1. Field of the invention

The present invention relates to a method and apparatus for encodingtelecine-converted video data for seamless connection and, moreparticularly to a bitstream for use in an authoring system for variouslyprocessing a data bitstream comprising the video data, audio data, andsub-picture data constituting each of plural program titles containingrelated video data, audio data, and sub-picture data content to generatea bitstream from which a new title containing the content desired by theuser can be reproduced, and efficiently recording and reproducing saidgenerated bitstream using a particular recording medium.

2. Description of the prior art

Authoring systems used to produce program titles comprising relatedvideo data, audio data, and sub-picture data by digitally processing,for example, multimedia data comprising video, audio, and sub-picturedata recorded to laser disk or video CD formats are currently available.

Systems using Video-CDs in particular are able to record video data to aCD format disk, which was originally designed with an approximately 600MB recording capacity for storing digital audio data only, by using suchhigh efficiency video compression techniques as MPEG. As a result of theincreased effective recording capacity achieved using data compressiontechniques, karaoke titles and other conventional laser diskapplications are gradually being transferred to the video CD format.

Users today expect both sophisticated title content and highreproduction quality. To meet these expectations, each title must becomposed from bitstreams with an increasingly deep hierarchicalstructure. The data size of multimedia titles written with bitstreamshaving such deep hierarchical structures, however, is ten or more timesgreater than the data size of less complex titles. The need to editsmall image (title) details also makes it necessary to process andcontrol the bitstream using low order hierarchical data units.

It is therefore necessary to develop and prove a bitstream structure andan advanced digital processing method including both recording andreproduction capabilities whereby a large volume, multiple levelhierarchical digital bitstream can be efficiently controlled at eachlevel of the hierarchy. Also needed are an apparatus for executing thisdigital processing method, and a recording media to which the bitstreamdigitally processed by said apparatus can be efficiently recorded forstorage and from which said recorded information can be quicklyreproduced.

Means of increasing the storage capacity of conventional optical diskshave been widely researched to address the recording medium aspect ofthis problem. One way to increase the storage capacity of the opticaldisk is to reduce the spot diameter D of the optical (laser) bean. Ifthe wavelength of the laser beam is 1 and the aperture of the objectivelens is NA, then the spot diameter D is proportional to 1/NA, and thestorage capacity can be efficiently improved by decreasing 1 andincreasing NA.

As described, for example, in U.S. Pat. No. 5,235,581, however, comacaused by a relative tilt between the disk surface and the optical axisof the laser beam (hereafter "tilt") increases when a large aperture(high NA) lens is used. To prevent tilt-induced coma, the transparentsubstrate must be made very thin. The problem is that the mechanicalstrength of the disk is low when the transparent substrate is very thin.

MPEG1, the conventional method of recording and reproducing video,audio, and graphic signal data, has also been replaced by the morerobust MPEG2 method, which can transfer large data volumes at a higherrate. It should be noted that the compression method and data format ofthe MPEG2 standard differ somewhat from those of RPEG1. The specificcontent of and differences between MPEG1 and MPEG2 are described indetail in the ISO-11172 and ISO-13818 MPEG standards, and furtherdescription thereof is omitted below.

Note, however, that while the structure of the encoded video stream isdefined in the MPEG2 specification, the hierarchical structure of thesystem stream and the method of processing lower hierarchical levels arenot defined.

As described above, it is therefore not possible in a conventionalauthoring system to process a large data stream containing sufficientinformation to satisfy many different user requirements. Moreover, evenif such a processing method were available, the processed data recordedthereto cannot be repeatedly used to reduce data redundancy becausethere is no large capacity recording medium currently available that canefficiently record and reproduce high volume bitstreams such asdescribed above.

More specifically, particular significant hardware and softwarerequirements must be satisfied in order to process a bitstream using adata unit smaller than the title. These specific hardware requirementsinclude significantly increasing the storage capacity of the recordingmedium and increasing the speed of digital processing; softwarerequirements include inventing an advanced digital processing methodincluding a sophisticated data structure.

Therefore, the object of the present invention is to provide aneffective authoring system for controlling a multimedia data bitstreamwith advanced hardware and software requirements using a data unitsmaller than the title to better address advanced user requirements.

Connecting a media player for reproducing the title content contained insuch multimedia data to a television receiver so that a user can easilyaccess and use the reproduced information is also desirable. Movies andother materials originally recorded on film will also be commonly usedas the source titles. When the bitstream is generated for recording,digital VCRs are used to supply the title content to the recordingsignal generator because of the ease of editing. Title content, such asmovies, recorded on film must be converted to a video format by means ofa frame rate conversion process, called "tele-cine conversion," and thisframe-converted signal is then used to produce the recording signal.

"Tele-cinema" conversion basically accomplishes the frame rateconversion by inserting at a regular period a redundant field copying afield with the same parity. Because there is not a simple integer ratiobetween the film frame rate and video frame rate, a conversion patternthat differs from the normal pattern is inserted to the gaps in thisregular insertion process. When the resulting tele-cine converted signalis then compression coded, the copied redundant fields will also becoded if compression coding is applied at the video frame rate. Codingredundant field information is obviously inefficient. As a result,compression coding is applied after a reverse telecine conversionprocess whereby the copied redundant fields are detected and removed. Inthis case, a flag indicating whether a redundant field has been removed,and a flag defining the presentation order of the two fields in theframe, are both recorded with each frame.

However, when the video objects VOB for plural title editing units towhich this reverse tele-cine conversion process has been applied areconnected and reproduced, the top field continues at the seam betweenthe contiguously reproduced VOB. MPEG decoder behavior is not generallyguaranteed in such cases. In a DVD player, a field may be inserted ordeleted, resulting at best in incoherent image reproduction and at worstin the insertion of a completely unrelated, and therefore meaningless,field. Even in the best-case scenario, i.e., incoherent imagereproduction, synchronization with the audio may be lost. As a result,true seamless reproduction cannot be achieved.

Therefore, the object of the present invention is to provide a datastructure whereby seamless reproduction can be achieved even at cellborders without the bottom fields from two connected frames or the topfields from two connected frames being connected when video objects VOBare seamlessly reproduced; a method for generating a system streamhaving said data structure; a recording apparatus and a reproductionapparatus for recording and reproducing said system stream; and anoptical disk medium and optical disk recording method for recording saidsystem stream.

The present application is based upon Japanese Patent Application No.7-252733, which was filed on Sep. 29, 1995, the entire contents of whichare expressly incorporated by reference herein.

SUMMARY OF THE INVENTION

The present invention has been developed with a view to substantiallysolving the above described disadvantages and has for its essentialobject to provide a seamless encoding method for telecine-convertedvideo data.

In order to achieve the aforementioned objective, a signal conversionrecording method applies a signal recording method whereby a videosignal converted to a frame rate greater than the frame rate of thesignal source by repeating particular fields plural times is convertedto an intermediate signal having a frame rate substantially equal to theframe rate of the original signal source by deleting these repeatedredundant fields, this intermediate signal is compression coded toobtain the recording signal, and the recording signal is recorded to arecording medium together with a repeat first field flag RFF declaringwhether a field was deleted, and a top field first flag TFF declaringwhich of the two fields in each of the resulting frames is first on thetime-base, wherein when plural logical recording periods are provided ona single recording medium, said video signal is converted to therecording signal so that said flags hold particular values at the startand end of each recording period.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given below and the accompanying diagrams wherein:

These and other objects and features of the present invention willbecome clear from the following description taken in conjunction withthe preferred embodiments thereof with reference to the accompanyingdrawings throughout which like parts are designated by like referencenumerals, and in which:

FIG. 1 is a graph schematically showing a structure of multi media bitstream according to the present invention,

FIG. 2 is a block diagram showing an authoring encoder according to thepresent invention,

FIG. 3 is a block diagram showing an authoring decoder according to thepresent invention,

FIG. 4 is a side view of an optical disk storing the multi media bitstream of FIG. 1,

FIG. 5 is an enlarged view showing a portion confined by a circle ofFIG. 4,

FIG. 6 is an enlarged view showing a portion confined by a circle ofFIG. 5,

FIG. 7 is a side view showing a variation of the optical disk of FIG. 4,

FIG. 8 is a side view showing another variation of the optical disk ofFIG. 4,

FIG. 9 is a plan view showing one example of track path formed on therecording surface of the optical disk of FIG. 4,

FIG. 10 is a plan view showing another example of track path formed onthe recording surface of the optical disk of FIG. 4,

FIG. 11 is a diagonal view schematically showing one example of a trackpath pattern formed on the optical disk of FIG. 7,

FIG. 12 is a plan view showing another example of track path formed onthe recording surface of the optical disk of FIG. 7,

FIG. 13 is a diagonal view schematically showing one example of a trackpath pattern formed on the optical disk of FIG. 8,

FIG. 14 is a plan view showing another example of track path formed onthe recording surface of the optical disk of FIG. 8,

FIG. 15 is a graph in assistance of explaining a concept of parentalcontrol according to the present invention,

FIG. 16 is a graph schematically showing the structure of multimedia bitstream for use in Digital Video Disk system according to the presentinvention,

FIG. 17 is a graph schematically showing the encoded video streamaccording to the present invention,

FIG. 18 is a graph schematically showing an internal structure of avideo zone of FIG. 16.

FIG. 19 is a graph schematically showing the stream managementinformation according to the present invention,

FIG. 20 is a graph schematically showing the structure the navigationpack NV of FIG. 17,

FIG. 21 in a graph is assistance of explaining a concept of parentallock playback control according to the present invention,

FIG. 22 is a graph schematically showing the data structure used in adigital video disk system according to the present invention,

FIG. 23 is a graph in assistance of explaining a concept of Multi-anglescene control according to the present invention,

FIG. 24 is a graph in assistance of explaining a concept of multi scenedata connection,

FIG. 25 is a block diagram showing a DVD encoder according to thepresent invention,

FIG. 26 is a block diagram showing a DVD decoder according to thepresent invention,

FIG. 27 is a graph schematically showing an encoding information tablegenerated by the encoding system controller of FIG. 25,

FIG. 28 is a graph schematically showing encoding information tables,

FIG. 29 is a graph schematically showing encoding parameters used by thevideo encoder of FIG. 25,

FIG. 30 is a graph schematically showing an example of the contents ofthe program chain information according to the present invention,

FIG. 31 is a graph schematically showing another example of the contentsof the program chain information according to the present invention,

FIG. 32 is a graph in assistance of the telecine conversion from thefilm material to a video signal,

FIG. 33 is a graph in assistance of explaining a concept of multi-anglescene control according to the present invention,

FIG. 34 is a flow chart, formed by FIGS. 34A and 34B, showing anoperation of the DVD encoder of FIG. 25,

FIG. 35 is a flow chart showing details of the encode parameterproduction sub-routine of FIG. 34,

FIG. 36 is a flow chart showing the details of the VOB data settingroutine of FIG. 35,

FIG. 37 is a flow chart showing the encode parameters generatingoperation for a seamless switching,

FIG. 38 is a flow chart showing the encode parameters generatingoperation for a system stream,

FIG. 39 is a block diagram showing an alternative of the video encoderof FIG. 25,

FIG. 40 and FIG. 41 are graphs showing telecine conversion,

FIG. 42 is a graph in assistance of explaining a reverse frame-rateconverting operation by the frame-rate converter of FIG. 25,

FIGS. 43 and 44 are graphs in assistance of the operations of the VOBend detector and redundant field removal controller,

FIG. 45 is a block diagram showing a modification of the video encoder300 of FIG. 39,

FIG. 46 is a graph in assistance of explaining an operation of the videoencoder 3 of FIG. 45,

FIGS. 47 and 48 are graphs showing decoding information table producedby the decoding system controller of FIG. 26,

FIG. 49 is a flow chart showing the operation of the DVD decoder DCD ofFIG. 26,

FIG. 50 is a flow chart showing details of reproduction extracted PGCrouting of FIG. 49,

FIG. 51 is a flow chart showing details of decoding data process of FIG.50, performed by the stream buffer,

FIG. 52 is a flow chart showing details of the decoder synchronizationprocess of FIG. 51,

FIG. 53 is a flow chart showing the encode parameters generatingoperation for a system stream containing a single scene,

FIG. 54 is a graph schematically showing an actual arrangement of datablocks recorded to a data recording track on a recording mediumaccording to the present invention,

FIG. 55 is a graph schematically showing contiguous block regions andinterleaved block regions array,

FIG. 56 is a graph schematically showing a content of a VTS title VOBS(VTSTT VOBS) according to the present invention, and

FIG. 57 is a graph schematically showing an internal data structure ofthe interleaved block regions according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Data Structure of the Authoring System

The logic structure of the multimedia data bitstream processed using therecording apparatus, recording medium, reproduction apparatus, andauthoring system according to the present invention is described firstbelow with reference to FIG. 1.

In this structure, one title refers to the combination of video andaudio data expressing program content recognized by a user foreducation, entertainment, or other purpose. Referenced to a motionpicture (movie), one title may correspond to the content of an entiremovie, or to just one scene within said movie.

A video title set (VTS) comprises the bitstream data containing theinformation for a specific number of titles. More specifically, each VTScomprises the video, audio, and other reproduction data representing thecontent of each title in the set, and control data for controlling thecontent data.

The video zone VZ is the video data unit processed by the authoringsystem, and comprises a specific number of video title sets. Morespecifically, each video zone is a linear sequence of K+1 video titlesets numbered VTS #0 -VTS #K where K is an integer value of zero orgreater. One video title set, preferably the first video title set VTS#0, is used as the video manager describing the content information ofthe titles contained in each video title set.

The multimedia bitstream MBS is the largest control unit of themultimedia data bitstream handled by the authoring system of the presentinvention, and comprises plural video zones VZ.

Authoring Encoder EC

A preferred embodiment of the authoring encoder EC according to thepresent invention for generating a new multimedia bitstream MBS byre-encoding the original multimedia bitstream MBS according to thescenario desired by the user is shown in FIG. 2. Note that the originalmultimedia bitstream MBS comprises a video stream St1 containing thevideo information, a sub-picture stream St3 containing caption text andother auxiliary video information, and the audio stream St5 containingthe audio information.

The video and audio streams are the bitstreams containing the video andaudio information obtained from the source within a particular period oftime. The sub-picture stream is a bitstream containing momentary videoinformation relevant to a particular scene. The sub-picture data encodedto a single scene may be captured to video memory and displayedcontinuously from the video memory for plural scenes as may benecessary.

When this multimedia source data St1, St3, and St5 is obtained from alive broadcast, the video and audio signals are supplied in real-timefrom a video camera or other imaging source; when the multimedia sourcedata is reproduced from a video tape or other recording medium, theaudio and video signals are not real-time signals.

While the multimedia source stream is shown in FIG. 2 as comprisingthese three source signals, this is for convenience only, and it shouldbe noted that the multimedia source stream may contain more than threetypes of source signals, and may contain source data for differenttitles. Multimedia source data with audio, video, and sub-picture datafor plural titles are referred to below as multi-title streams.

As shown in FIG. 2, the authoring encoder EC comprises a scenario editor100, encoding system controller 200, video encoder 300, video streambuffer 400, sub-picture encoder 500, sub-picture stream buffer 600,audio encoder 700, audio stream buffer 800, system encoder 900, videozone formatter 1300, recorder 1200, and recording medium M.

The video zone formatter 1300 comprises video object (VOB) buffer 1000,formatter 1100, and volume and file structure formatter 1400.

The bitstream encoded by the authoring encoder EC of the presentembodiment is recorded by way of example only to an optical disk.

The scenario editor 100 of the authoring encoder EC outputs the scenariodata, i.e., the user-defined editing instructions. The scenario datacontrols editing the corresponding parts of the multimedia bitstream MBSaccording to the user's manipulation of the video, sub-picture, andaudio components of the original multimedia title. This scenario editor100 preferably comprises a display, speaker(s), keyboard, CPU, andsource stream buffer. The scenario editor 100 is connected to anexternal multimedia bitstream source from which the multimedia sourcedata St1, St3, and St5 are supplied.

The user is thus able to reproduce the video and audio components of themultimedia source data using the display and speaker to confirm thecontent of the generated title. The user is then able to edit the titlecontent according to the desired scenario using the keyboard, mouse, andother command input devices while confirming the content of the title onthe display and speakers. The result of this multimedia datamanipulation is the scenario data St7.

The scenario data St7 is basically a set of instructions describing whatsource data is selected from all or a subset of the source datacontaining plural titles within a defined time period, and how theselected source data is reassembled to reproduce the scenario (sequence)intended by the user. Based on the instructions received through thekeyboard or other control device, the CPU codes the position, length,and the relative time-based positions of the edited parts of therespective multimedia source data streams St1, St3, and St5 to generatethe scenario data St7.

The source stream buffer has a specific capacity, and is used to delaythe multimedia source data streams St1, St3, and St5 a known time Td andthen output streams St1, St3, and St5.

This delay is required for synchronization with the editor encodingprocess. More specifically, when data encoding and user generation ofscenario data St7 are executed simultaneously, i.e., when encodingimmediately follows editing, time Td is required to determine thecontent of the multimedia source data editing process based on thescenario data St7 as will be described further below. As a result, themultimedia source data must be delayed by time Td to synchronize theediting process during the actual encoding operation. Because this delaytime Td is limited to the time required to synchronize the operation ofthe various system components in the case of sequential editing asdescribed above, the source stream buffer is normally achieved by meansof a high speed storage medium such as semiconductor memory.

During batch editing in which all multimedia source data is encoded atonce ("batch encoded") after scenario data St7 is generated for thecomplete title, delay time Td must be long enough to process thecomplete title or longer. In this case, the source stream buffer may bea low speed, high capacity storage medium such as video tape, magneticdisk, or optical disk.

The structure (type) of media used for the source stream buffer maytherefore be determined according to the delay time Td required and theallowable manufacturing cost.

The encoding system controller 200 is connected to the scenario editor100 and receives the scenario data St7 therefrom. Based on the time-baseposition and length information of the edit segment contained in thescenario data St7, the encoding system controller 200 generates theencoding parameter signals St9, St11, and St13 for encoding the editsegment of the multimedia source data. The encoding signals St9, St11,and St13 supply the parameters used for video, sub-picture, and audioencoding, including the encoding start and end timing. Note thatmultimedia source data St1, St3, and St5 are output after delay time Tdby the source stream buffer, and are therefore synchronized to encodingparameter signals St9, St11, and St13.

More specifically, encoding parameter signal St9 is the video encodingsignal specifying the encoding timing of video stream St1 to extract theencoding segment from the video stream St1 and generate the videoencoding unit. Encoding parameter signal St11 is likewise thesub-picture stream encoding signal used to generate the sub-pictureencoding unit by specifying the encoding timing for sub-picture streamSt3. Encoding parameter signal St13 is the audio encoding signal used togenerate the audio encoding unit by specifying the encoding timing foraudio stream St5.

Based on the time-base relationship between the encoding segments ofstreams St1, St3, and St5 in the multimedia source data contained inscenario data St7, the encoding system controller 200 generates thetiming signals St21, St23, and St25 arranging the encodedmultimedia-encoded stream in the specified time-base relationship.

The encoding system controller 200 also generates the reproduction timeinformation IT defining the reproduction time of the title editing unit(video object, VOB), and the stream encoding data St33 defining thesystem encode parameters for multiplexing the encoded multimedia streamcontaining video, audio, and sub-picture data. Note that thereproduction time information IT and stream encoding data St33 aregenerated for the video object VOB of each title in one video zone Vz.

The encoding system controller 200 also generates the title sequencecontrol signal St39, which declares the formatting parameters forformatting the title editing units VOB of each of the streams in aparticular time-base relationship as a multimedia bitstream. Morespecifically, the title sequence control signal St39 is used to controlthe connections between the title editing units (VOB) of each title inthe multimedia bitstream MBS, or to control the sequence of theinterleaved title editing unit (VOBs) interleaving the title editingunits VOB of plural reproduction paths.

The video encoder 300 is connected to the source stream buffer of thescenario editor 100 and to the encoding system controller 200, andreceives therefrom the video stream St1 and video encoding parametersignal St9, respectively. Encoding parameters supplied by the videoencoding signal St9 include the encoding start and end timing, bit rate,the encoding conditions for the encoding start and end, and the materialtype. Possible material types include NTSC or PAL video signal, andtelecine converted material. Based on the video encoding parametersignal St9, the video encoder 300 encodes a specific part of the videostream St1 to generate the encoded video stream St15.

The sub-picture encoder 500 is similarly connected to the source streambuffer of the scenario editor 100 and to the encoding system controller200, and receives therefrom the sub-picture stream St3 and sub-pictureencoding parameter signal St11, respectively. Based on the sub-pictureencoding parameter signal St11, the sub-picture encoder 500 encodes aspecific part of the sub-picture stream St3 to generate the encodedsub-picture stream St17.

The audio encoder 700 is also connected to the source stream buffer ofthe scenario editor 100 and to the encoding system controller 200, andreceives therefrom the audio stream St5 and audio encoding parametersignal St13, which supplies the encoding start and end timing. Based onthe audio encoding parameter signal St13, the audio encoder 700 encodesa specific part of the audio stream St5 to generate the encoded audiostream St19.

The video stream buffer 400 is connected to the video encoder 300 and tothe encoding system controller 200. The video stream buffer 400 storesthe encoded video stream St15 input from the video encoder 300, andoutputs the stored encoded video stream St15 as the time-delayed encodedvideo stream St27 based on the timing signal St21 supplied from theencoding system controller 200.

The sub-picture stream buffer 600 is similarly connected to thesub-picture encoder 500 and to the encoding system controller 200. Thesub-picture stream buffer 600 stores the encoded sub-picture stream St17output from the sub-picture encoder 500, and then outputs the storedencoded sub-picture stream St17 as time-delayed encoded sub-picturestream St29 based on the timing signal St23 supplied from the encodingsystem controller 200.

The audio stream buffer 800 is similarly connected to the audio encoder700 and to the encoding system controller 200. The audio stream buffer800 stores the encoded audio stream St19 input from the audio encoder700, and then outputs the encoded audio stream St19 as the time-delayedencoded audio stream St31 based on the timing signal St25 supplied fromthe encoding system controller 200.

The system encoder 900 is connected to the video stream buffer 400,sub-picture stream buffer 600, audio stream buffer 800, and the encodingsystem controller 200, and is respectively supplied thereby with thetime-delayed encoded video stream St27, time-delayed encoded sub-picturestream St29, time-delayed encoded audio stream St31, and the streamencoding data St33. Note that the system encoder 900 is a multiplexerthat multiplexes the time-delayed streams St27, St29, and St31 based onthe stream encoding data St33 (timing signal) to generate title editingunit (VOB) St35. The stream encoding data St33 contains the systemencoding parameters, including the encoding start and end timing.

The video zone formatter 1300 is connected to the system encoder 900 andthe encoding system controller 200 from which the title editing unit(VOB) St35 and title sequence control signal St39 (timing signal) arerespectively supplied. The title sequence control signal St39 containsthe formatting start and end timing, and the formatting parameters usedto generate (format) a multimedia bitstream MBS. The video zoneformatter 1300 rearranges the title editing units (VOB) St35 in onevideo zone VZ in the scenario sequence defined by the user based on thetitle sequence control signal St39 to generate the edited multimediastream data St43.

The multimedia bitstream MBS St43 edited according to the user-definedscenario is then sent to the recorder 1200. The recorder 1200 processesthe edited multimedia stream data St43 to the data stream St45 format ofthe recording medium M, and thus records the formatted data stream St45to the recording medium M. Note that the multimedia bitstream MBSrecorded to the recording medium M contains the volume file structureVFS, which includes the physical address of the data on the recordingmedium generated by the video zone formatter 1300.

Note that the encoded multimedia bitstream MBS St35 may be outputdirectly to the decoder to immediately reproduce the edited titlecontent. It will be obvious that the output multimedia bitstream MBSwill not in this case contain the volume file structure VFS.

Authoring Decoder

A preferred embodiment of the authoring decoder DC used to decode themultimedia bitstream MBS edited by the authoring encoder EC of thepresent invention, and thereby reproduce the content of each title unitaccording to the user-defined scenario, is described next below withreference to FIG. 3. Note that in the preferred embodiment describedbelow the multimedia bitstream St45 encoded by the authoring encoder ECis recorded to the recording medium M.

As shown in FIG. 3, the authoring decoder DC comprises a multimediabitstream producer 2000, scenario selector 2100, decoding systemcontroller 2300, stream buffer 2400, system decoder 2500, video buffer2600, sub-picture buffer 2700, audio buffer 2800, synchronizer 2900,video decoder 3800, sub-picture decoder 3100, audio decoder 3200,synthesizer 3500, video data output terminal 3600, and audio data outputterminal 3700.

The bitstream producer 2000 comprises a recording media drive unit 2004for driving the recording medium M; a reading head 2006 for reading theinformation recorded to the recording medium M and producing the binaryread signal St57; a signal processor 2008 for variously processing theread signal St57 to generate the reproduced bitstream St61; and areproduction controller 2002.

The reproduction controller 2002 is connected to the decoding systemcontroller 2300 from which the multimedia bitstream reproduction controlsignal St53 is supplied, and in turn generates the reproduction controlsignals St55 and St59 respectively controlling the recording media driveunit (motor) 2004 and signal processor 2008.

So that the user-defined video, sub-picture, and audio portions of themultimedia title edited by the authoring encoder EC are reproduced, theauthoring decoder DC comprises a scenario selector 2100 for selectingand reproducing the corresponding scenes (titles). The scenario selector2100 then outputs the selected titles as scenario data to the authoringdecoder DC.

The scenario selector 2100 preferably comprises a keyboard, CPU, andmonitor. Using the keyboard, the user then inputs the desired scenariobased on the content of the scenario input by the authoring encoder EC.Based on the keyboard input, the CPU generates the scenario selectiondata St51 specifying the selected scenario. The scenario selector 2100is connected by an infrared communications device, for example, to thedecoding system controller 2300, to which it inputs the scenarioselection data St51.

Based on the scenario selection data St51, the decoding systemcontroller 2300 then generates the bitstream reproduction control signalSt53 controlling the operation of the bitstream producer 2000.

The stream buffer 2400 has a specific buffer capacity used totemporarily store the reproduced bitstream St61 input from the bitstreamproducer 2000, extract the address information and initialsynchronization data SCR (system clock reference) for each stream, andgenerate bitstream control data St63. The stream buffer 2400 is alsoconnected to the decoding system controller 2300, to which it suppliesthe generated bitstream control data St63.

The synchronizer 2900 is connected to the decoding system controller2300 from which it receives the system clock reference SCR contained inthe synchronization control data St81 to set the internal system clockSTC and supply the reset system clock St79 to the decoding systemcontroller 2300.

Based on this system clock St79, the decoding system controller 2300also generates the stream read signal St65 at a specific interval andoutputs the read signal St65 to the stream buffer 2400.

Based on the supplied read signal St65, the stream buffer 2400 outputsthe reproduced bitstream St61 at a specific interval to the systemdecoder 2500 as bitstream St67.

Based on the scenario selection data St51, the decoding systemcontroller 2300 generates the decoding signal St69 defining the streamIds for the video, sub-picture, and audio bitstreams corresponding tothe selected scenario, and outputs to the system decoder 2500.

Based on the instructions contained in the decoding signal St69, thesystem decoder 2500 respectively outputs the video, sub-picture, andaudio bitstreams input from the stream buffer 2400 to the video buffer2600, sub-picture buffer 2700, and audio buffer 2800 as the encodedvideo stream St71, encoded sub-picture stream St73, and encoded audiostream St75.

The system decoder 2500 detects the presentation time stamp PTS anddecoding time stamp DTS of the smallest control unit in each bitstreamSt67 to generate the time information signal St77. This time informationsignal St77 is supplied to the synchronizer 2900 through the decodingsystem controller 2300 as the synchronization control data St81.

Based on this synchronization control data St81, the synchronizer 2900determines the decoding start timing whereby each of the bitstreams willbe arranged in the correct sequence after decoding, and then generatesand inputs the video stream decoding start signal St89 to the videodecoder 3800 based on this decoding timing. The synchronizer 2900 alsogenerates and supplies the sub-picture decoding start signal St91 andaudio stream decoding start signal St93 to the sub-picture decoder 3100and audio decoder 3200, respectively.

The video decoder 3800 generates the video output request signal St84based on the video stream decoding start signal St89, and outputs to thevideo buffer 2600. In response to the video output request signal St84,the video buffer 2600 outputs the video stream St83 to the video decoder3800. The video decoder 3800 thus detects the presentation timeinformation contained in the video stream St83, and disables the videooutput request signal St84 when the length of the received video streamSt83 is equivalent to the specified presentation time. A video streamequal in length to the specified presentation time is thus decoded bythe video decoder 3800, which outputs the reproduced video signal St104to the synthesizer 3500.

The sub-picture decoder 3100 similarly generates the sub-picture outputrequest signal St86 based on the sub-picture decoding start signal St91,and outputs to the sub-picture buffer 2700. In response to thesub-picture output request signal St86, the sub-picture buffer 2700outputs the sub-picture stream St85 to the sub-picture decoder 3100.Based on the presentation time information contained in the sub-picturestream St85, the sub-picture decoder 3100 decodes a length of thesub-picture stream St85 corresponding to the specified presentation timeto reproduce and supply to the synthesizer 3500 the sub-picture signalSt99.

The synthesizer 3500 superimposes the video signal St104 and sub-picturesignal St99 to generate and output the multi-picture video signal St105to the video data output terminal 3600.

The audio decoder 3200 generates and supplies to the audio buffer 2800the audio output request signal StS8 based on the audio stream decodingstart signal St93. The audio buffer 2800 thus outputs the audio streamSt87 to the audio decoder 3200. The audio decoder 3200 decodes a lengthof the audio stream St87 corresponding to the specified presentationtime based on the presentation time information contained in the audiostream St87, and outputs the decoded audio stream St101 to the audiodata output terminal 3700.

It is thus possible to reproduce a user-defined multimedia bitstream MBSin real-time according to a user-defined scenario. More specifically,each time the user selects a different scenario, the authoring decoderDC is able to reproduce the title content desired by the user in thedesired sequence by reproducing the multimedia bitstream MBScorresponding to the selected scenario.

It is therefore possible by means of the authoring system of the presentinvention to generate a multimedia bitstream according to pluraluser-defined scenarios by real-time or batch encoding multimedia sourcedata in a manner whereby the substreams of the smallest editing units(scenes), which can be divided into plural substreams, expressing thebasic title content are arranged in a specific time-base relationship.

The multimedia bitstream thus encoded can then be reproduced accordingto the one scenario selected from among plural possible scenarios. It isalso possible to change scenarios while playback is in progress, i.e.,to select a different scenario and dynamically generate a new multimediabitstream according to the most recently selected scenario. It is alsopossible to dynamically select and reproduce any of plural scenes whilereproducing the title content according to a desired scenario.

It is therefore possible by means of the authoring system of the presentinvention to encode and not only reproduce but to repeatedly reproduce amultimedia bitstream MBS in real-time.

A detail of the authoring system is disclosed Japanese PatentApplication filed Sep. 27, 1996, and entitled and assigned to the sameassignee as the present application.

Digtital Video Disk (DVD)

An example of a digital video disk (DVD) with only one recording surface(a single-sided DVD) is shown in FIG. 4.

The DVD recording medium RC1 in the preferred embodiment of theinvention comprises a data recording surface RS1 to and from which datais written and read by emitting laser beam LS, and a protective layerPL1 covering the data recording surface RS1. A backing layer BL1 is alsoprovided on the back of data recording surface RS1. The side of the diskon which protective layer PL1 is provided is therefore referred to belowas side SA (commonly "side A"), and the opposite side (on which thebacking layer BL1 is provided) is referred to as side SB ("side B").Note that digital video disk recording media having a single datarecording surface RS1 on only one side such as this DVD recording mediumRC1 is commonly called a single-sided single layer disk.

A detailed illustration of area C1 in FIG. 4 is shown in FIG. 5. Notethat the data recording surface RS1 is formed by applying a metallicthin film or other reflective coating as a data layer 4109 on a firsttransparent layer 4108 having a particular thickness T1. This firsttransparent layer 4108 also functions as the protective layer PL1. Asecond transparent substrate 4111 of a thickness T2 functions as thebacking layer BL1, and is bonded to the first transparent layer 4108 bymeans of an adhesive layer 4110 disposed therebetween.

A printing layer 4112 for printing a disk label may also be disposed onthe second transparent substrate 4111 as necessary. The printing layer4112 does not usually cover the entire surface area of the secondtransparent substrate 4111 (backing layer BL1), but only the area neededto print the text and graphics of the disk label. The area of secondtransparent substrate 4111 to which the printing layer 4112 is notformed may be left exposed. Light reflected from the data layer 4109(metallic thin film) forming the data recording surface RS1 cantherefore be directly observed where the label is not printed when thedigital video disk is viewed from side SB. As a result, the backgroundlooks like a silver-white over which the printed text and graphics floatwhen the metallic thin film is an aluminum thin film, for example.

Note that it is only necessary to provide the printing layer 4112 whereneeded for printing, and it is not necessary to provide the printinglayer 4112 over the entire surface of the backing layer BL1.

A detailed illustration of area C2 in FIG. 5 is shown in FIG. 6. Pitsand lands are molded to the common contact surface between the firsttransparent layer 4108 and the data layer 4109 on side SA from whichdata is read by emitting a laser beam LS, and data is recorded byvarying the lengths of the pits and lands (i.e., the length of theintervals between the pits). More specifically, the pit and landconfiguration formed on the first transparent layer 4108 is transferredto the data layer 4109. The lengths of the pits and lands is shorter,and the pitch of the data tracks formed by the pit sequences isnarrower, than with a conventional Compact Disc (CD). The surfacerecording density is therefore greatly improved.

Side SA of the first transparent layer 4108 on which data pits are notformed is a flat surface. The second transparent substrate 4111 is forreinforcement, and is a transparent panel made from the same material asthe first transparent layer 4108 with both sides flat. Thicknesses T1and T2 are preferably equal and commonly approximately 0.6 mm, but theinvention shall not be so limited.

As with a CD, information is read by irradiating the surface with alaser beam LS and detecting the change in the reflectivity of the lightspot. Because the objective lens aperture NA can be large and thewavelength 1 of the light beam small in a digital video disk system, thediameter of the light spot Ls used can be reduced to approximately 1/1.6the light spot needed to read a CD. Note that this means the resolutionof the laser beam LS in the DVD system is approximately 1.6 times theresolution of a conventional CD system.

The optical system used to read data from the digital video disk uses ashort 650 nm wavelength red semiconductor laser and an objective lenswith a 0.6 mm aperture NA. By thus also reducing the thickness T of thetransparent panels to 0.6 mm, more than 5 GB of data can be stored toone side of a 120 mm diameter optical disk.

It is therefore possible to store notion picture (video) images havingan extremely large per unit data size to a digital video disk systemdisk without losing image quality because the storage capacity of asingle-sided, single-layer recording medium RC1 with one data recordingsurface RS1 as thus described is nearly ten times the storage capacityof a conventional CD. As a result, while the video presentation time ofa conventional CD system is approximately 74 minutes if image quality issacrificed, high quality video images with a video presentation timeexceeding two hours can be recorded to a DVD.

The digital video disk is therefore well-suited as a recording mediumfor video images.

A digital video disk recording medium with plural recording surfaces RSas described above is shown in FIGS. 7 and 8. The DVD recording mediumRC2 shown in FIG. 7 comprises two recording surfaces, i.e., firstrecording surface RS1 and semi-transparent second recording surface RS2,on the same side, i.e. side SA, of the disk. Data can be simultaneouslyrecorded or reproduced from these two recording surfaces by usingdifferent laser beams LS1 and LS2 for the first recording surface RS1and the second recording surface RS2. It is also possible to read/writeboth recording surfaces RS1 and RS2 using only one of the laser beamsLS1 or LS2. Note that recording media thus comprised are called"single-side, dual-layer disks."

It should also be noted that while two recording surfaces RS1 and RS2are provided in this example, it is also possible to produce digitalvideo disk recording media having more than two recording surfaces RS.Disks thus comprised are known as "single-sided, multi-layer disks."

Though comprising two recording surfaces similarly to the recordingmedia shown in FIG. 7, the DVD recording medium RC3 shown in FIG. 8 hasthe recording surfaces on opposite sides of the disk, i.e., has thefirst data recording surface RS1 on side SA and the second datarecording surface RS2 on side SB. It will also be obvious that whileonly two recording surfaces are shown on one digital video disk in thisexample, more than two recording surfaces may also be formed on adouble-sided digital video disk. As with the recording medium shown inFIG. 7, it is also possible to provide two separate laser beams LS1 andLS2 for recording surfaces RS1 and RS2, or to read/write both recordingsurfaces RS1 and RS2 using a single laser beam. Note that this type ofdigital video disk is called a "double-sided, dual-layer disk." It willalso be obvious that a double-sided digital video disk can be comprisedwith two or more recording surfaces per side. This type of disk iscalled a "double-sided, multi-layer disk."

A plan view from the laser beam LS irradiation side of the recordingsurface RS of the DVD recording medium RC is shown in FIG. 9 and FIG.10. Note that a continuous spiral data recording track TR is providedfrom the inside circumference to the outside circumference of the DVD.The data recording track TR is divided into plural sectors each havingthe same known storage capacity. Note that for simplicity only the datarecording track TR is shown in FIG. 9 with more than three sectors perrevolution.

As shown in FIG. 9, the data recording track TR is normally formedclockwise inside to outside (see arrow DrA) from the inside end point IAat the inside circumference of disk RCA to the outside end point OA atthe outside circumference of the disk with the disk RCA rotatingcounterclockwise RdA. This type of disk RCA is called a clockwise disk,and the recording track formed thereon is called a clockwise track TRA.

Depending upon the application, the recording track TRB may be formedclockwise from outside to inside circumference (see arrow DrB in FIG.10) from the outside end point OB at the outside circumference of diskRCB to the inside end point IB at the inside circumference of the diskwith the disk RCB rotating clockwise RdB. Because the recording trackappears to wind counterclockwise when viewed from the insidecircumference to the outside circumference on disks with the recordingtrack formed in the direction of arrow DrB, these disks are referred toas counterclockwise disk RCB with counterclockwise track TRB todistinguish them from disk RCA in FIG. 9. Note that track directions DrAand DrB are the track paths along which the laser beam travels whenscanning the tracks for recording and playback. Direction of diskrotation RdA in which disk RCA turns is thus opposite the direction oftrack path DrA direction of disk rotation RdB in which disk RCB turns isthus opposite the direction of track path DrB.

An exploded view of the single-sided, dual-layer disk RC2 shown in FIG.7 is shown as disk RC20 in FIG. 11. Note that the recording tracksformed on the two recording surfaces run in opposite directions.Specifically, a clockwise recording track TRA as shown in FIG. 9 isformed in clockwise direction DrA on the (lower) first data recordingsurface RS1, and a counterclockwise recording track TRB formed incounterclockwise direction DrB as shown in FIG. 10 is provided on the(upper) second data recording surface RS2. As a result, the outside endpoints OA and OB of the first and second (top and bottom) tracks are atthe same radial position relative to the center axis of the disk RC2o.Note that track paths DrA and DrB of tracks TR are also the dataread/write directions to disk RC. The first and second (top and bottom)recording tracks thus wind opposite each other with this disk RC, i.e.,the track paths DrA and DrB of the top and bottom recording layers areopposite track paths.

Opposite track path type, single-sided, dual-layer disks RC2o rotate indirection RdA corresponding to the first recording surface RS1 with thelaser beam LS traveling along track path DrA to trace the recordingtrack on the first recording surface RS1. When the laser beam LS reachesthe outside end point OA, the laser beam LS can be refocused to endpoint OB on the second recording surface RS2 to continue tracing therecording track from the first to the second recording surfaceuninterrupted. The physical distance between the recording tracks TRAand TRB on the first and second recording surfaces RS1 and RS2 can thusbe instantaneously eliminated by simply adjusting the focus of the laserbeam LS.

It is therefore possible with an opposite track path type, single-sided,dual-layer disk RC2o to easily process the recording tracks disposed tophysically discrete top and bottom recording surfaces as a singlecontinuous recording track. It is therefore also possible in anauthoring system as described above with reference to FIG. 1 tocontinuously record the multimedia bitstream MBS that is the largestmultimedia data management unit to two discrete recording surfaces RS1and RS2 on a single recording medium RC2o.

It should be noted that the tracks on recording surfaces RS1 and RS2 canbe wound in the directions opposite those described above, i.e., thecounterclockwise track TRB may be provided on the first recordingsurface RS1 and the clockwise track TRA on the second recording surfaceRS2. In this case the direction of disk rotation is also changed to aclockwise rotation RdB, thereby enabling the two recording surfaces tobe used as comprising a single continuous recording track as describedabove. For simplification, a further example of this type of disk istherefore neither shown nor described below.

It is therefore possible by thus constructing the digital video disk torecord the multimedia bitstream MBS for a feature-length title to asingle opposite track path type, single-sided, dual-layer disk RC2o.Note that this type of digital video disk medium is called asingle-sided dual-layer disk with opposite track paths.

Another example of the single-sided, dual-layer DVD recording medium RC2shown in FIG. 7 is shown as disk RC2p in FIG. 12. The recording tracksformed on both first and second recording surfaces RS1 and RS2 areclockwise tracks TRA as shown in FIG. 9. In this case, the single-sided,dual-layer disk RC2p rotates counterclockwise in the direction of arrowRdA, and the direction of laser beam LS travel is the same as thedirection of the track spiral, i.e., the track paths of the top andbottom recording surfaces are mutually parallel (parallel track paths).The outside end points OA of both top and bottom tracks are againpreferably positioned at the same radial position relative to the centeraxis of the disk RC2p as described above. As also described above withdisk RC2o shown in FIG. 11, the access point can be instantaneouslyshifted from outside end point OA of track TRA on the first recordingsurface RS1 to the outside end point OA of track TRA on the secondrecording surface RS2 by appropriately adjusting the focus of the laserbeam LS at outside end point OA.

However, for the laser beam LS to continuously access the clockwiserecording track TRA on the second recording surface RS2, the recordingmedium RC2p must be driven in the opposite direction (clockwise,opposite direction RdA). Depending on the radial position of the laserbeam LS, however, it is inefficient to change the rotational directionof the recording medium. As shown by the diagonal arrow in FIG. 12, thelaser beam LS is therefore moved from the outside end point OA of thetrack on the first recording surface RS1 to the inside end point IA ofthe track on the second recording surface RS2 to use these physicallydiscrete recording tracks as one logically continuous recording track.

Rather than using the recording tracks on top and bottom recordingsurfaces as one continuous recording track, it is also possible to usethe recording tracks to record the multimedia bitstreams NBS fordifferent titles. This type of digital video disk recording medium iscalled a "single-sided, dual-layer disk with parallel track paths."

Note that if the direction of the tracks formed on the recordingsurfaces RS1 and RS2 is opposite that described above, i.e.,counterclockwise recording tracks TRB are formed, disk operation remainsthe same as that described above except for the direction of diskrotation, which is clockwise as shown by arrow RdB.

Whether using clockwise or counterclockwise recording tracks, thesingle-sided, dual-layer disk RC2p with parallel track paths thusdescribed is well-suited to storing on a single disk encyclopedia andsimilar multimedia bitstreams comprising multiple titles that arefrequently and randomly accessed.

An exploded view of the dual-sided single-layer DVD recording medium RC3comprising one recording surface layer RS1 and RS2 on each side as shownin FIG. 8 is shown as DVD recording medium RC3s in FIG. 13. Clockwiserecording track TRA is provided on the one recording surface RS1, and acounterclockwise recording track TRB is provided on the other recordingsurface RS2. As in the preceding recording media, the outside end pointsOA and OB of the recording tracks on each recording surface arepreferably positioned at the same radial position relative to the centeraxis of the DVD recording medium RC3s.

Note that while the recording tracks on these recording surfaces RS1 andRS2 rotate in opposite directions, the track paths are symmetrical. Thistype of recording medium is therefore known as a double-sided dual layerdisk with symmetrical track paths. This double-sided dual layer diskwith symmetrical track paths RC3s rotates in direction RdA whenreading/writing the first recording surface RS1. As a result, the trackpath on the second recording surface RS2 on the opposite side isopposite the direction DrB in which the track winds, i.e., directionDrA. Accessing both recording surfaces RS1 and RS2 using a single laserbeam LS is therefore not realistic irrespective of whether access iscontinuous or non-continuous. In addition, a multimedia bitstream MBS isseparately recorded to the recording surfaces on the first and secondsides of the disk.

A different example of the double-sided single layer disk RC3 shown inFIG. 8 is shown in FIG. 14 as disk RC3a. Note that this disk comprisesclockwise recording tracks TRA as shown in FIG. 9 on both recordingsurfaces RS1 and RS2. As with the preceding recording media, the outsideend points OA and OA of the recording tracks on each recording surfaceare preferably positioned at the same radial position relative to thecenter axis of the DVD recording medium RC3a. Unlike the double-sideddual layer disk with symmetrical track paths RC3s described above, thetracks on these recording surfaces RS1 and RS2 are asymmetrical. Thistype of disk is therefore known as a double-sided dual layer disk withasymmetrical track paths. This double-sided dual layer disk withasymmetrical track paths RC3a rotates in direction RdA whenreading/writing the first recording surface RS1. As a result, the trackpath on the second recording surface RS2 on the opposite side isopposite the direction DrA in which the track winds, i.e., directionDrB.

This means that if a laser beam LS is driven continuously from theinside circumference to the outside circumference on the first recordingsurface RS1, and then from the outside circumference to the insidecircumference on the second recording surface RS2, both sides of therecording medium RC3a can be read/written without turning the disk overand without providing different laser beams for the two sides.

The track paths for recording surfaces RS1 and RS2 are also the samewith this double-sided dual layer disk with asymmetrical track pathsRC3a. As a result, it is also possible to read/write both sides of thedisk without providing separate laser beams for each side if therecording medium RC3a is turned over between sides, and the read/writeapparatus can therefore be constructed economically.

It should be noted that this recording medium remains functionallyidentical even if counterclockwise recording track TRB is provided inplace of clockwise recording track TRA on both recording surfaces RS1and RS2.

As described above, the true value of a DVD system whereby the storagecapacity of the recording medium can be easily increased by using amultiple layer recording surface is realized in multimedia applicationswhereby plural video data units, plural audio data units, and pluralgraphics data units recorded to a single disk are reproduced throughinteractive operation by the user.

It is therefore possible to achieve one long-standing desire of software(programming) providers, specifically, to provide programming contentsuch as a commercial movie on a single recording medium in pluralversions for different language and demographic groups while retainingthe image quality of the original.

Parental Control

Content providers of movie and video titles have conventionally had toproduce, supply, and manage the inventory of individual titles inmultiple languages, typically the language of each distribution market,and multi-rated title packages conforming to the parental control(censorship) regulations of individual countries in Europe and NorthAmerica. The time and resources required for this are significant. Whilehigh image quality is obviously important, the programming content mustalso be consistently reproducible.

The digital video disk recording medium is close to solving theseproblems.

Multiple Angles

One interactive operation widely sought in multimedia applications todayis for the user to be able to change the position from which a scene isviewed during reproduction of that scene. This capability is achieved bymeans of the multiple angle function.

This multiple angle function makes possible applications whereby, forexample, a user can watch a baseball game from different angles (orvirtual positions in the stadium), and can freely switch between theviews while viewing is in progress. In this example of a baseball game,the available angles may include a position behind the backstop centeredon the catcher, batter, and pitcher; one from behind the backstopcentered on a fielder, the pitcher, and the catcher; and one from centerfield showing the view to the pitcher and catcher.

To meet these requirements, the digital video disk system uses MPEG, thesame basic standard format used with Video-Cds to record the video,audio, graphics, and other signal data. Because of the differences instorage capacity, transfer rates, and signal processing performancewithin the reproduction apparatus, DVD uses MPEG2, the compressionmethod and data format of which differ slightly from the MPEG1 formatused with Video-Cds.

It should be noted that the content of and differences between the MPEG1and MPEG2 standards have no direct relationship to the intent of thepresent invention, and further description is therefore omitted below(for more information, see MPEG specifications ISO-11172 and ISO-13818).

The data structure of the DVD system according to the present inventionis described in detail below with reference to FIGS. 16, 17, 18, 19, 20,and 21.

Multi-Scene Control

A fully functional and practical parental lock playback function andmulti-angle scene playback function must enable the user to modify thesystem output in minor, subtle ways while still presenting substantiallythe same video and audio output. If these functions are achieved bypreparing and recording separate titles satisfying each of the manypossible parental lock and multi-angle scene playback requests, titlesthat are substantially identical and differ in only minor ways must berecorded to the recording medium. This results in identical data beingrepeatedly recorded to the larger part of the recording medium, andsignificantly reduces the utilization efficiency of the availablestorage capacity. More particularly, it is virtually impossible torecord discrete titles satisfying every possible request even using themassive capacity of the digital video disk medium. While it may beconcluded that this problem can be easily solved by increasing thecapacity of the recording medium, this is an obviously undesirablesolution when the effective use of available system resources isconsidered.

Using multi-scene control, the concept of which is described in anothersection below, in a DVD system, it is possible to dynamically constructtitles for numerous variations of the same basic content using thesmallest possible amount of data, and thereby effectively utilize theavailable system resources (recording medium). More specifically, titlesthat can be played back with numerous variations are constructed frombasic (common) scene periods containing data common to each title, andmulti-scene periods comprising groups of different scenes correspondingto the various requests. During reproduction, the user is able to freelyand at any time select particular scenes from the multi-scene periods todynamically construct a title conforming to the desired content, e.g., atitle omitting certain scenes using the parental lock control function.

Note that multi-scene control enabling a parental lock playback controlfunction and multi-angle scene playback is described in another sectionbelow with reference to FIG. 21.

Data Structure of the DVD System

The data structure used in the authoring system of a digital video disksystem according to the present invention is shown in FIG. 22. To recorda multimedia bitstream MBS, this digital video disk system divides therecording medium into three major recording areas, the lead-in area LI,the volume space VS, and the lead-out area LO.

The lead-in area LI is provided at the inside circumference area of theoptical disk. In the disks described with reference to FIGS. 9 and 10,the lead-in area LI is positioned at the inside end points IA and IB ofeach track. Data for stabilizing the operation of the reproducingapparatus when reading starts is written to the lead-in area LI.

The lead-out area LO is correspondingly located at the outsidecircumference of the optical disk, i.e., at outside end points OA and OBof each track in the disks described with reference to FIGS. 9 and 10.Data identifying the end of the volume space VS is recorded in thislead-out area LO.

The volume space VS is located between the lead-in area LI and lead-outarea LO, and is recorded as a one-dimensional array of n+1 (where n isan integer greater than or equal to zero) 2048-byte logic sectors LS.The logic sectors LS are sequentially number #0, #1, #2, . . . #n. Thevolume space VS is also divided into a volume and file structuremanagement area VFS and a file data structure area FDS.

The volume and file structure management area VFS comprises m+1 logicsectors LS#0 to LS#m (where m is an integer greater than or equal tozero and less than n. The file data structure FDS comprises n-m logicsectors LS #m+1 to LS #n.

Note that this file data structure area FDS corresponds to themultimedia bitstream FBS shown in FIG. 1 and described above.

The volume file structure VFS is the file system for managing the datastored to the volume space VS as files, and is divided into logicsectors LS#0-LS#m where m is the number of sectors required to store alldata needed to manage the entire disk, and is a natural number less thann. Information for the files stored to the file data structure area FDSis written to the volume file structure VFS according to a knownspecification such as ISO-9660 or ISO-13346.

The file data structure area FDS comprises n-m logic sectors LS#m-LS#n,each comprising a video manager VMG sized to an integer multiple of thelogic sector (2048×I, where I is a known integer), and k video titlesets VTS #1 -VTS#k (where k is a natural number less than 100).

The video manager VMG stores the title management information for theentire disk, and information for building a volume menu used to set andchange reproduction control of the entire volume.

Any video title set VTS #k is also called a "video file" representing atitle comprising video, audio, and/or still image data.

The internal structure of each video title set VTS shown in FIG. 22 isshown in FIG. 16. Each video title set VTS comprises VTS informationVTSI describing the management information for the entire disk, and theVTS title video objects VOB (VTSTT₋₋ VOBS), i.e., the system stream ofthe multimedia bitstream. The VTS information VTSI is described firstbelow, followed by the VTS title VOBS.

The VTS information primarily includes the VTSI management table VTSI₋₋MAT and VTSPGC information table VTS₋₋ PGCIT.

The VTSI management table VTSI₋₋ MAT stores such information as theinternal structure of the video title set VTS, the number of selectableaudio streams contained in the video title set VTS, the number ofsub-pictures, and the video title set VTS location (storage address).

The VTSPGC information table VTS₋₋ PGCIT records i (where i is a naturalnumber) program chain (PGC) data blocks VTS₋₋ PGCI #1-VTS₋₋ PGCI #i forcontrolling the playback sequence. Each of the table entries VTS₋₋ PGCI#i is a data entry expressing the program chain, and comprises j (wherej is a natural number) cell playback information blocks C₋₋ PBI #1-C₋₋PBI #j. Each cell playback information block C₋₋ PBI #j contains theplayback sequence of the cell and playback control information.

The program chain PGC is a conceptual structure describing the story ofthe title content, and therefore defines the structure of each title bydescribing the cell playback sequence. Note that these cells aredescribed in detail below.

If, for example, the video title set information relates to the menus,the video title set information VTSI is stored to a buffer in theplayback device when playback starts. If the user then presses a MENUbutton on a remote control device, for example, during playback, theplayback device references the buffer to fetch the menu information anddisplay the top menu #1. If the menus are hierarchical, the main menustored as program chain information VTS₋₋ PGCI #1 may be displayed, forexample, by pressing the NENU button, VTS₋₋ PGCI #2-#9 may correspond tosubmenus accessed using the numeric keypad on the remote control, andVTS₋₋ PGCI #10 and higher may correspond to additional submenus furtherdown the hierarchy. Alternatively, VTS₋₋ PGCI #1 may be the top menudisplayed by pressing the MENU button, while VTS₋₋ PGCI #2 and highermay be voice guidance reproduced by pressing the corresponding numerickey.

The menus themselves are expressed by the plural program chains definedin this table. As a result, the menus may be freely constructed invarious ways, and shall not be limited to hierarchical ornon-hierarchical menus or menus containing voice guidance.

In the case of a movie, for example, the video title set informationVTSI is stored to a buffer in the playback device when playback starts,the playback device references the cell playback sequence described bythe program chain PGC, and reproduces the system stream.

The "cells" referenced here may be all or part of the system stream, andare used as access points during playback. Cells can therefore be used,for example, as the "chapters" into which a title may be divided.

Note that each of the PGC information entries C₋₋ PBI #j contain bothcell playback processing information and a cell information table. Thecell playback processing information comprises the processinginformation needed to reproduce the cell, such as the presentation timeand number of repetitions. More specifically, this information includesthe cell block mode CBM, cell block type CBT, seamless playback flagSPF, interleaved allocation flag IAF, STC resetting flag STCDF, cellpresentation time C₋₋ PBTM, seamless angle change flag SACF, first cellVOBU start address C₋₋ FVOBU₋₋ SA, and the last cell VOBU start addressC₋₋ LVOBU₋₋ SA.

Note that seamless playback refers to the reproduction in a digitalvideo disk system of multimedia data including video, audio, andsub-picture data without intermittent breaks in the data or information.Seamless playback is described in detail in another section below withreference to FIG. 23 and FIG. 24.

The cell block mode CBM indicates whether plural cells constitute onefunctional block. The cell playback information of each cell in afunctional block is arranged consecutively in the PGC information. Thecell block mode CBM of the first cell playback information in thissequence contains the value of the first cell in the block, and the cellblock mode CBM of the last cell playback information in this sequencecontains the value of the last cell in the block. The cell block modeCBM of each cell arrayed between these first and last cells contains avalue indicating that the cell is a cell between these first and lastcells in that block.

The cell block type CBT identifies the type of the block indicated bythe cell block mode CBM. For example, when a multiple angle function isenabled, the cell information corresponding to each of the reproducibleangles is programmed as one of the functional blocks mentioned above,and the type of these functional blocks is defined by a valueidentifying "angle" in the cell block type CBT for each cell in thatblock.

The seamless playback flag SPF simply indicates whether thecorresponding cell is to be linked and played back seamlessly with thecell or cell block reproduced immediately therebefore. To seamlesslyreproduce a given cell with the preceding cell or cell block, theseamless playback flag SPF is set to 1 in the cell playback informationfor that cell; otherwise SPF is set to 0.

The interleaved allocation flag IAF stores a value identifying whetherthe cell exists in a contiguous or interleaved block. If the cell ispart of an interleaved block, the flag IAF is set to 1; otherwise it isset to 0.

The STC resetting flag STCDF identifies whether the system time clockSTC used for synchronization must be reset when the cell is played back;when resetting the system time clock STC is necessary, the STC resettingflag STCDF is set to 1.

The seamless angle change flag SACF stores a value indicating whether acell in a multi-angle period should be connected seamlessly at an anglechange. If the angle change is seamless, the seamless angle change flagSACF is set to 1; otherwise it is set to 0.

The cell presentation time C₋₋ PBTM expresses the cell presentation timewith video frame precision.

The first cell VOBU start address C₋₋ FVOBU₋₋ SA is the VOBU startaddress of the first cell in a block, and is also expressed as thedistance from the logic sector of the first cell in the VTS title VOBS(VTSTT₋₋ VOBS) as measured by the number of sectors.

The last cell VOBU start address C₋₋ LVOBU₋₋ SA is the VOBU startaddress of the last cell in the block. The value of this address isexpressed as the distance from the logic sector of the first cell in theVTS title VOBS (VTSTT₋₋ VOBS) as measured by the number of sectors.

The VTS title VOBS (VTSTT₋₋ VOBS), i.e., the multimedia system streamdata, is described next. The system stream data VTSTT₋₋ VOBS comprises i(where i is a natural number) system streams SS, each of which isreferred to as a "video object" (VOB). Each video object VOB #1-VOB #icomprises at least one video data block interleaved with up to a maximumeight audio data blocks and up to a maximum 32 sub-picture data blocks.

Each video object VOB comprises q (where q is a natural number) cellsC#1-C#q. Each cell C comprises r (where r is a natural number) videoobject units VOBU #1-VOBU #r.

Each video object unit VOBU comprises plural groups₋₋ of₋₋ pictures GOP,and the audio and sub-pictures corresponding to the playback of saidplural groups₋₋ of₋₋ pictures GOP. Note that the group₋₋ of₋₋ picturesGOP corresponds to the video encoding refresh cycle. Each video objectunit VOBU also starts with an NV pack, i.e., the control data for thatVOBU.

The structure of the navigation packs NV is described with reference toFIG. 18.

Before describing the navigation pack NV, the internal structure of thevideo zone VZ (see FIG. 22), i.e., the system stream St35 encoded by theauthoring encoder EC described with reference to FIG. 25, is describedwith reference to FIG. 17. Note that the encoded video stream St15 shownin FIG. 17 is the compressed one-dimensional video data stream encodedby the video encoder 300. The encoded audio stream St19 is likewise thecompressed one-dimensional audio data stream multiplexing the right andleft stereo audio channels encoded by the audio encoder 700. Note thatthe audio signal shall not be limited to a stereo signal, and nay alsobe a multichannel surround-sound signal.

The system stream (title editing unit VOB) St35 is a one dimensionalarray of packs with a byte size corresponding to the logic sectors LS #nhaving a 2048-byte capacity as described using FIG. 21. A stream controlpack is placed at the beginning of the title editing unit (VOB) St35,i.e., at the beginning of the video object unit VOBU. This streamcontrol pack is called the "navigation pack NV", and records the dataarrangement in the system stream and other control information.

The encoded video stream St15 and the encoded audio stream St19 arepacketized in byte units corresponding to the system stream packs. Thesepackets are shown in FIG. 17 as packets V1, V2, V3, V4 . . . and A1, A2,A3 . . . As shown in FIG. 17, these packets are interleaved in theappropriate sequence as system stream St35, thus forming a packetstream, with consideration given to the decoder buffer size and the timerequired by the decoder to expand the video and audio data packets. Inthe example shown in FIG. 17, the packet stream is interleaved in thesequence V1, V2, A1, V3, V4, A2 . . . .

Note that the sequence shown in FIG. 17 interleaves one video data unitwith one audio data unit. Significantly increased recording/playbackcapacity, high speed recording/playback, and performance improvements inthe signal processing LSI enable the DVD system to record plural audiodata and plural sub-picture data (graphics data) to one video data unitin a single interleaved MPEG system stream, and thereby enable the userto select the specific audio data and sub-picture data to be reproducedduring playback. The structure of the system stream used in this type ofDVD system is shown in FIG. 18 and described below.

As in FIG. 17, the packetized encoded video stream St15 is shown in FIG.18 as V1, V2, V3, V4, . . . In this example, however, there is not justone encoded audio stream St19, but three encoded audio streams St19A,St19B, and St19C input as the source data. There are also two encodedsub-picture streams St17A and St17B input as the source data sub-picturestreams. These six compressed data streams, St15, St19A, St19B, St19C,St17A and St17B, are interleaved to a single system stream St35.

The video data is encoded according to the MPEG specification with thegroup₋₋ of₋₋ pictures GOP being the unit of compression. In general,each group₋₋ of₋₋ pictures GOP contains 15 frames in the case of an NTSCsignal, but the specific number of frames compressed to one GOP isvariable. The stream management pack, which describes the managementdata containing, for example, the relationship between interleaved data,is also interleaved at the GOP unit interval. Because the group₋₋ of₋₋pictures GOP unit is based on the video data, changing the number ofvideo frames per GOP unit changes the interval of the stream managementpacks. This interval is expressed in terms of the presentation time onthe digital video disk within a range from 0.4 sec. to 1.0 sec.referenced to the GOP unit. If the presentation time of contiguousplural GOP units is less than 1 sec., the management data packs for thevideo data of the plural GOP units is interleaved to a single stream.

These management data packs are referred to as navigation packs NV inthe digital video disk system. The data from one navigation pack NV tothe packet immediately preceding the next navigation pack NV forms onevideo object unit VOBU. In general, one contiguous playback unit thatcan be defined as one scene is called a video object VOB, and each videoobject VOB contains plural video object units VOBU. Data sets of pluralvideo objects VOB form a VOB set (VOBS). Note that these data units werefirst used in the digital video disk.

When plural of these data streams are interleaved, the navigation packsNV defining the relationship between the interleaved packs must also beinterleaved at a defined unit known as the pack number unit. Eachgroup₋₋ of₋₋ pictures GOP is normally a unit containing approximately0.5 sec. of video data, which is equivalent to the presentation timerequired for 12-15 frames, and one navigation pack NV is generallyinterleaved with the number of data packets required for thispresentation time.

The stream management information contained in the interleaved video,audio, and sub-picture data packets constituting the system stream isdescribed below with reference to FIG. 19 As shown in FIG. 19, the datacontained in the system stream is recorded in a format packed orpacketized according to the MPEG2 standard. The packet structure isessentially the same for video, audio, and sub-picture data. One pack inthe digital video disk system has a 2048 byte capacity as describedabove, and contains a pack header PKH and one packet PES; each packetPES contains a packet header PTH and data block.

The pack header PKH records the time at which that pack is to be sentfrom stream buffer 2400 to system decoder 2500 (see FIG. 26), i.e., thesystem clock reference SCR defining the reference time for synchronizedaudio-visual data playback. The MPEG standard assumes that the systemclock reference SCR is the reference clock for the entire decoderoperation. With such disk media as the digital video disk, however, timemanagement specific to individual disk players can be used, and areference clock for the decoder system is therefore separately provided.

The packet header PTH similarly contains a presentation time stamp PTSand a decoding time stamp DTS, both of which are placed in the packetbefore the access unit (the decoding unit). The presentation time stampPTS defines the time at which the video data or audio data contained inthe packet should be output as the playback output after being decoded,and the decoding time stamp DTS defines the time at which the videostream should be decoded. Note that the presentation time stamp PTSeffectively defines the display start timing of the access unit, and thedecoding time stamp DTS effectively defines the decoding start timing ofthe access unit. If the PTS and DTS are the same time, the DTS isomitted.

The packet header PTH also contains an 8-bit field called the stream IDidentifying the packet type, i.e., whether the packet is a video packetcontaining a video data stream, a private packet, or an MPEG audiopacket.

Private packets under the MPEG2 standard are data packets of which thecontent can be freely defined. Private packet 1 in this embodiment ofthe invention is used to carry audio data other than the MPEG audiodata, and sub-picture data; private packet 2 carries the PCI packet andDSI packet.

Private packets 1 and 2 each comprise a packet header, private dataarea, and data area. The private data area contains an 8-bit sub-streamID indicating whether the recorded data is audio data or sub-picturedata. The audio data defined by private packet 2 may be defined as anyof eight types #0 -#7 of linear PCM or AC-3 encoded data. Sub-picturedata may be defined as one of up to 32 types #0-#31.

The data area is the field to which data compressed according to theMPEG2 specification is written if the stored data is video data; linearPCM, AC-3, or MPEG encoded data is written if audio data is stored; orgraphics data compressed by runlength coding is written if sub-picturedata is stored.

MPEG2-compressed video data may be compressed by constant bit rate (CBR)or variable bit rate (VBR) coding. With constant bit rate coding, thevideo stream is input continuously to the video buffer at a constantrate. This contrasts with variable bit rate coding in which the videostream is input intermittently to the video buffer, thereby making itpossible to suppress the generation of unnecessary code. Both constantbit rate and variable bit rate coding can be used in the digital videodisk system.

Because MPEG video data is compressed with variable length coding, thedata quantity in each group₋₋ of₋₋ pictures GOP is not constant. Thevideo and audio decoding times also differ, and the time-baserelationship between the video and audio data read from an optical disk,and the time-base relationship between the video and audio data outputfrom the decoder, do not match. The method of time-base synchronizingthe video and audio data is therefore described in detail below withreference to FIG. 26, but is described briefly below based on constantbit rate coding.

The navigation pack NV structure is shown in FIG. 20. Each navigationpack NV starts with a pack header PKH, and contains a PCI packet and DSIpacket.

As described above, the pack header PKH records the time at which thatpack is to be sent from stream buffer 2400 to system decoder 2500 (seeFIG. 26), i.e., the system clock reference SCR defining the referencetime for synchronized audio-visual data playback.

Each PCI packet contains PCI General Information (PCI₋₋ GI) and AngleInformation for Non-seamless playback (NMSL₋₋ AGLI).

The PCI General Information (PCI₋₋ GI) declares the display time of thefirst video frame (the Start PTM of VOBU (VOBU₋₋ S₋₋ PTM)), and thedisplay time of the last video frame (End PTM of VOBU (VOBU₋₋ E₋₋ PTM)),in the corresponding video object unit VOBU with system clock precision(90 Khz).

The Angle Information for Non-seamless playback (NMSL₋₋ AGLI) states theread start address of the corresponding video object unit VOBU when theangle is changed expressed as the number of sectors from the beginningof the video object VOB. Because there are nine or fewer angles in thisexample, there are nine angle address declaration cells: DestinationAddress of Angle Cell #1 for Non-seamless playback (NMSL₋₋ AGL₋₋ C1₋₋DSTA) to Destination Address of Angle Cell #9 for Non-seamless playback(NMSL₋₋ AGL₋₋ C9₋₋ DSTA).

Each DSI packet contains DSI General Information (DSI₋₋ GI), SeamlessPlayback Information (SML₋₋ PBI), and Angle Information for Seamlessplayback (SML₋₋ AGLI).

The DSI General Information (DSI₋₋ GI) declares the address of the lastpack in the video object unit VOBU, i. e., the End Address for VOB(VOBU₋₋ EA), expressed as the number of sectors from the beginning ofthe video object unit VOBU.

While seamless playback is described in detail later, it should be notedthat the continuously read data units must be interleaved (multiplexed)at the system stream level as an interleaved unit ILVU in order toseamlessly reproduce split or combined titles. Plural system streamsinterleaved with the interleaved unit ILVU as the smallest unit aredefined as an interleaved block.

The Seamless Playback Information (SML₋₋ PBI) is declared to seamlesslyreproduce the stream interleaved with the interleaved unit ILVU as thesmallest data unit, and contains an Interleaved Unit Flag (ILVU flag)identifying whether the corresponding video object unit VOBU is aninterleaved block. The ILVU flag indicates whether the video object unitVOBU is in an interleaved block, and is set to 1 when it is. Otherwisethe ILVU flag is set to 0.

When a video object unit VOBU is in an interleaved block, a Unit ENDflag is declared to indicate whether the video object unit VOBU is thelast VOBU in the interleaved unit ILVU. Because the interleaved unitILVU is the data unit for continuous reading, the Unit END flag is setto 1 if the VOBU currently being read is the last VOBU in theinterleaved unit ILVU. Otherwise the Unit END flag is set to 0.

An Interleaved Unit End Address (ILVU₋₋ EA) identifying the address ofthe last pack in the ILVU to which the VOBU belongs, and the startingaddress of the next interleaved unit ILVU, Next Interleaved Unit StartAddress (NT₋₋ ILVU₋₋ SA), are also declared when a video object unitVOBU is in an interleaved block. Both the Interleaved Unit End Address(ILVU₋₋ EA) and Next Interleaved Unit Start Address (NT₋₋ ILVU₋₋ SA) areexpressed as the number of sectors from the navigation pack NV of thatVOBU.

When two system streams are seamlessly connected but the audiocomponents of the two system streams are not contiguous, particularlyimmediately before and after the seam, it is necessary to pause theaudio output to synchronize the audio and video components of the systemstream following the seam. Note that non-contiguous audio may resultfrom different audio signals being recording with the correspondingvideo blocks. With an NTSC signal, for example, the video frame cycle isapproximately 33. 33 msec while the AC-3 audio frame cycle is 32 msec.

To enable this resynchronization, audio are production stopping times 1and 2, i.e., Audio Stop PTM 1 in VOB (VOB₋₋ A₋₋ STP₋₋ PTM1), and AudioStop PTM2 in VOB (VOB₋₋ A₋₋ STP₋₋ PTM2), indicating the time at whichthe audio is to be paused; and audio reproduction stopping periods 1 and2, i.e., Audio Gap Length 1 in VOB (VOB₋₋ A₋₋ GAP₋₋ LEN1) and Audio GapLength 2 in VOB (VOB₋₋ A₋₋ GAP₋₋ LEN2), indicating for how long theaudio is to be paused, are also declared in the DSI packet. Note thatthese times are specified at the system clock precision (90 Khz).

The Angle Information for Seamless playback (SML₋₋ AGLI) declares theread start address when the angle is changed. Note that this field isvalid when seamless, multi-angle control is enabled. This address isalso expressed as the number of sectors from the navigation pack NV ofthat VOBU. Because there are nine or fewer angles, there are nine angleaddress declaration cells: Destination Address of Angle Cell #1 forSeamless playback (SML₋₋ AGL₋₋ C1₋₋ DSTA) to Destination Address ofAngle Cell #9 for Seamless playback (SML₋₋ AGL₋₋ C9₋₋ DSTA).

Note also that each title is edited in video object (VOB) units.Interleaved video objects (interleaved title editing units) arereferenced as "VOBS"; and the encoded range of the source data is theencoding unit.

DVD Encoder

A preferred embodiment of a digital video disk system authoring encoderECD in which the multimedia bitstream authoring system according to thepresent invention is applied to a digital video disk system is describedbelow and shown in FIG. 25. It will be obvious that the authoringencoder ECD applied to the digital video disk system, referred to belowas a DVD encoder, is substantially identical to the authoring encoder ECshown in FIG. 2. The basic difference between these encoders is thereplacement in the DVD encoder ECD of the video zone formatter 1300 ofthe authoring encoder EC above with a VOB buffer 1000 and formatter1100. It will also be obvious that the bitstream encoded by this DVDencoder ECD is recorded to a digital video disk medium M. The operationof this DVD encoder ECD is therefore described below in comparison withthe authoring encoder EC described above.

As in the above authoring encoder EC, the encoding system controller 200generates control signals St9, St11, St13, St21, St23, St25, St33, andSt39 based on the scenario data St7 describing the user-defined editinginstructions input from the scenario editor 100, and controls the videoencoder 300, sub-picture encoder 500, and audio encoder 700 in the DVDencoder ECD. Note that the user-defined editing instructions in the DVDencoder ECD are a superset of the editing instructions of the authoringencoder EC described above.

Specifically, the user-defined editing instructions (scenario data St7)in the DVD encoder ECD similarly describe what source data is selectedfrom all or a subset of the source data containing plural titles withina defined time period, and how the selected source data is reassembledto reproduce the scenario (sequence) intended by the user. The scenariodata St7 of the DVD encoder ECD, however, further contains suchinformation as: the number of streams contained in the editing units,which are obtained by splitting a multi-title source stream into blocksat a constant time interval; the number of audio and sub-picture datacells contained in each stream, and the sub-picture display time andperiod; whether the title is a multi-rated title enabling parental lockcontrol; whether the user content is selected from plural streamsincluding, for example, multiple viewing angles; and the method ofconnecting scenes when the angle is switched among the multiple viewingangles.

The scenario data St7 of the DVD encoder ECD also contains controlinformation on a video object VOB unit basis. This information isrequired to encode the media source stream, and specifically includessuch information as whether there are multiple angles or parentalcontrol features. When multiple angle viewing is enabled, the scenariodata St7 also contains the encoding bit rate of each stream consideringdata interleaving and the disk capacity, the start and end times of eachcontrol, and whether a seamless connection should be made between thepreceding and following streams.

The encoding system controller 200 extracts this information from thescenario data St7, and generates the encoding information table andencoding parameters required for encoding control. The encodinginformation table and encoding parameters are described with referenceto FIGS. 27, 28, and 29 below.

The stream encoding data St33 contains the system stream encodingparameters and system encoding start and end timing values required bythe DVD system to generate the VOBs. These system stream encodingparameters include the conditions for connecting one video object VOBwith those before and after, the number of audio streams, the audioencoding information and audio Ids, the number of sub-pictures and thesub-picture Ids, the video playback starting time information VPTS, andthe audio playback starting time information APTS.

The title sequence control signal St39 supplies the multimedia bitstreamMBS formatting start and end timing information and formattingparameters declaring the reproduction control information and interleaveinformation.

Based on the video encoding parameter and encoding start/end timingsignal St9, the video encoder 300 encodes a specific part of the videostream St1 to generate an elementary stream conforming to the MPEG2Video standard defined in ISO-13818. This elementary stream is output tothe video stream buffer 400 as encoded video stream St15.

Note that while the video encoder 300 generates an elementary streamconforming to the MPEG2 Video standard defined in ISO-13818, specificencoding parameters are input via the video encoding parameter signalSt9, including the encoding start and end timing, bit rate, the encodingconditions for the encoding start and end, the material type, includingwhether the material is an NTSC or PAL video signal or telecineconverted material, and whether the encoding mode is set for either openGOP or closed GOP encoding.

The MPEG2 coding method is basically an interframe coding method usingthe correlation between frames for maximum signal compression, i.e., theframe being coded (the target frame) is coded by referencing framesbefore and/or after the target frame. However, intra-coded frames, i.e.,frames that are coded based solely on the content of the target frame,are also inserted to avoid error propagation and enable accessibilityfrom mid-stream (random access). The coding unit containing at least oneintra-coded frame ("intra-frame") is called a group₋₋ of₋₋ pictures GOP.

A group₋₋ of₋₋ pictures GOP in which coding is closed completely withinthat GOP is known as a "closed GOP." A group₋₋ of₋₋ pictures GOPcontaining a frame coded with reference to a frame in a preceding orfollowing (ISO-13818 DOES NOT LIMIT P-and B-picture CODING toreferencing PAST frames) group₋₋ of₋₋ pictures GOP is an "open GOP." Itis therefore possible to playback a closed GOP using only that GOP.Reproducing an open GOP, however, also requires the presence of thereferenced GOP, generally the GOP preceding the open GOP.

The GOP is often used as the access unit. For example, the GOP may beused as the playback start point for reproducing a title from themiddle, as a transition point in a movie, or for fast-forward play andother special reproduction modes. High speed reproduction can beachieved in such cases by reproducing only the intra-frame coded framesin a GOP or by reproducing only frames in GOP units.

Based on the sub-picture stream encoding parameter signal St11, thesub-picture encoder 500 encodes a specific part of the sub-picturestream St3 to generate a variable length coded bitstream of bitmappeddata. This variable length coded bitstream data is output as the encodedsub-picture stream St17 to the sub-picture stream buffer 600.

Based on the audio encoding parameter signal St13, the audio encoder 700encodes a specific part of the audio stream St5 to generate the encodedaudio data. This encoded audio data may be data based on the VPEG1 audiostandard defined in ISO-11172 and the MPEG2 audio standard defined inISO-13818, AC-3 audio data, or PCM (LPCM) data. Note that the methodsand means of encoding audio data according to these standards are knownand commonly available.

The video stream buffer 400 is connected to the video encoder 300 and tothe encoding system controller 200. The video stream buffer 400 storesthe encoded video stream St15 input from the video encoder 300, andoutputs the stored encoded video stream St15 as the time-delayed encodedvideo stream St27 based on the timing signal St21 supplied from theencoding system controller 200.

The sub-picture stream buffer 600 is similarly connected to thesub-picture encoder 500 and to the encoding system controller 200. Thesub-picture stream buffer 600 stores the encoded sub-picture stream St17input from the sub-picture encoder 500, and then outputs the storedencoded sub-picture stream St17 as time-delayed encoded sub-picturestream St29 based on the timing signal St23 supplied from the encodingsystem controller 200.

The audio stream buffer 800 is similarly connected to the audio encoder700 and to the encoding system controller 200. The audio stream buffer800 stores the encoded audio stream St19 input from the audio encoder700, and then outputs the encoded audio stream St19 as the time-delayedencoded audio stream St31 based on the timing signal St25 supplied fromthe encoding system controller 200.

The system encoder 900 is connected to the video stream buffer 400,sub-picture stream buffer 600, audio stream buffer 800, and the encodingsystem controller 200, and is respectively supplied thereby with thetime-delayed encoded video stream St27, time-delayed encoded sub-picturestream St29, time-delayed encoded audio stream St31, and the systemstream encoding parameter data St33. Note that the system encoder 900 isa multiplexer that multiplexes the time-delayed streams St27, St29, andSt31 based on the stream encoding data St33 (timing signal) to generatetitle editing units (VOBS) St35.

The VOB buffer 1000 temporarily stores the video objects VOBs producedby the system encoder 900. The formatter 1100 reads the delayed videoobjects VOB from the VOB buffer 1000 based on the title sequence controlsignal St39 to generate one video zone VZ, and adds the volume filestructure VFS to generate the edited multimedia stream data St43.

The multimedia bitstream VBS St43 edited according to the user-definedscenario is then sent to the recorder 1200. The recorder 1200 processesthe edited multimedia stream data St43 to the data stream St45 format ofthe recording medium M, and thus records the formatted data stream St45to the recording medium M.

DVD Decoder

A preferred embodiment of a digital video disk system authoring decoderDCD in which the multimedia bitstream authoring system of the presentinvention is applied to a digital video disk system is described belowand shown in FIG. 26. The authoring decoder DCD applied to the digitalvideo disk system, referred to below as a DVD decoder DCD, decodes themultimedia bitstream MBS edited using the DVD encoder ECD of the presentinvention, and recreates the content of each title according to theuser-defined scenario. It will also be obvious that the multimediabitstream St45 encoded by this DVD encoder ECD is recorded to a digitalvideo disk medium M.

The basic configuration of the DVD decoder DCD according to thisembodiment is the same as that of the authoring decoder DC shown in FIG.3. The differences are that a different video decoder 3801 (shown as3801 in FIG. 26) is used in place of the video decoder 3800, and areordering buffer 3300 and selector 3400 are disposed between the videodecoder 3801 and synthesizer 3500.

Note that the selector 3400 is connected to the synchronizer 2900, andis controlled by a switching signal St103.

The operation of this DVD decoder DCD is therefore described below incomparison with the authoring decoder DC described above.

As shown in FIG. 26, the DVD decoder DCD comprises a multimediabitstream producer 2000, scenario selector 2100, decoding systemcontroller 2300, stream buffer 2400, system decoder 2500, video buffer2600, sub-picture buffer 2700, audio buffer 2800, synchronizer 2900,video decoder 3801, reordering buffer 3300, sub-picture decoder 3100,audio decoder 3200, selector 3400, synthesizer 3500, video data outputterminal 3600, and audio data output terminal 3700.

The bitstream producer 2000 comprises a recording media drive unit 2004for driving the recording medium M; a reading head 2006 for reading theinformation recorded to the recording medium M and producing the binaryread signal St57; a signal processor 2008 for variously processing theread signal St57 to generate the reproduced bitstream St61; and areproduction controller 2002.

The reproduction controller 2002 is connected to the decoding systemcontroller 2300 from which the multimedia bitstream reproduction controlsignal St53 is supplied, and in turn generates the reproduction controlsignals St55 and St59 respectively controlling the recording media driveunit (motor) 2004 and signal processor 2008.

So that the user-defined video, sub-picture, and audio portions of themultimedia title edited by the authoring encoder EC are reproduced, theauthoring decoder DC comprises a scenario selector 2100 for selectingand reproducing the corresponding scenes (titles). The scenario selector2100 then outputs the selected titles as scenario data to the DVDdecoder DCD.

The scenario selector 2100 preferably comprises a keyboard, CPU, andmonitor. Using the keyboard, the user then inputs the desired scenariobased on the content of the scenario input by the DVD encoder ECD. Basedon the keyboard input, the CPU generates the scenario selection dataSt51 specifying the selected scenario. The scenario selector 2100 isconnected to the decoding system controller 2300 by an infraredcommunications device, for example, and inputs the generated scenarioselection data St51 to the decoding system controller 2300.

The stream buffer 2400 has a specific buffer capacity used totemporarily store the reproduced bitstream St61 input from the bitstreamproducer 2000, extract the volume file structure VFS, the initialsynchronization data SCR (system clock reference) in each pack, and theVOBU control information (DSI) in the navigation pack NV, to generatethe bitstream control data St63. The stream buffer 2400 is alsoconnected to the decoding system controller 2300, to which it suppliesthe generated bitstream control data St63.

Based on the scenario selection data St51 supplied by the scenarioselector 2100, the decoding system controller 2300 then generates thebitstream reproduction control signal St53 controlling the operation ofthe bitstream producer 2000. The decoding system controller 2300 alsoextracts the user-defined playback instruction data from the bitstreamreproduction control signal St53, and generates the decoding informationtable required for decoding control. This decoding information table isdescribed further below with reference to FIGS. 47 and 48. The decodingsystem controller 2300 also extracts the title information recorded tothe optical disk M from the file data structure area FDS of thebitstream control data St63 to generate the title information signalSt200. Note that the extracted title information includes the videomanager VMG, VTS information VTSI, the PGC information entries C₋₋ PBI#j, and the cell presentation time C₋₋ PBTM.

Note that the bitstream control data St63 is generated in pack units asshown in FIG. 19, and is supplied from the stream buffer 2400 to thedecoding system controller 2300, to which the stream buffer 2400 isconnected.

The synchronizer 2900 is connected to the decoding system controller2300 from which it receives the system clock reference SCR contained inthe synchronization control data St81 to set the internal system clockSTC and supply the reset system clock St79 to the decoding systemcontroller 2300.

Based on this system clock St79, the decoding system controller 2300also generates the stream read signal St65 at a specific interval andoutputs the read signal St65 to the stream buffer 2400. Note that theread unit in this case is the pack.

The method of generating the stream read signal St65 is described next.

The decoding system controller 2300 compares the system clock referenceSCR contained in the stream control data extracted from the streambuffer 2400 with the system clock St79 supplied from the synchronizer2900, and generates the read request signal St65 when the system clockSt79 is greater than the system clock reference SCR of the bitstreamcontrol data St63. Pack transfers are controlled by executing thiscontrol process on a pack unit.

Based on the scenario selection data St51, the decoding systemcontroller 2300 generates the decoding signal St69 defining the streamIds for the video, sub-picture, and audio bitstreams corresponding tothe selected scenario, and outputs to the system decoder 2500.

When a title contains plural audio tracks, e.g. audio tracks inJapanese, English, French, and/or other languages, and pluralsub-picture tracks for subtitles in Japanese, English, French, and/orother languages, for example, a discrete ID is assigned to each of thelanguage tracks. As described above with reference to FIG. 19, a streamID is assigned to the video data and MPEG audio data, and a substream IDis assigned to the sub-picture data, AC-3 audio data, linear PCM data,and navigation pack NV information. While the user need never be awareof these ID numbers, the user can select the language of the audioand/or subtitles using the scenario selector 2100. If English languageaudio is selected, for example, the ID corresponding to the Englishaudio track is sent to the decoding system controller 2300 as scenarioselection data St51. The decoding system controller 2300 then adds thisID to the decoding signal St69 output to the system decoder 2500.

Based on the instructions contained in the decoding signal St69, thesystem decoder 2500 respectively outputs the video, sub-picture, andaudio bitstreams input from the stream buffer 2400 to the video buffer2600, sub-picture buffer 2700, and audio buffer 2800 as the encodedvideo stream St71, encoded sub-picture stream St73, and encoded audiostream St75. Thus, when the stream ID input from the scenario selector2100 and the pack ID input from the stream buffer 2400 match, the systemdecoder 2500 outputs the corresponding packs to the respective buffers(i.e., the video buffer 2600, sub-picture buffer 2700, and audio buffer2800).

The system decoder 2500 detects the presentation time stamp PTS anddecoding time stamp DTS of the smallest control unit in each bitstreamSt67 to generate the time information signal St77. This time informationsignal St77 is supplied to the synchronizer 2900 through the decodingsystem controller 2300 as the synchronization control data St81.

Based on this synchronization control data St81, the synchronizer 2900determines the decoding start timing whereby each of the bitstreams willbe arranged in the correct sequence after decoding, and then generatesand inputs the video stream decoding start signal St89 to the videodecoder 3801 based on this decoding timing. The synchronizer 2900 alsogenerates and supplies the sub-picture decoding start signal St91 andaudio stream decoding start signal St93 to the sub-picture decoder 3100and audio decoder 3200, respectively.

The video decoder 3801 generates the video output request signal St84based on the video stream decoding start signal St89, and outputs to thevideo buffer 2600. In response to the video output request signal St84,the video buffer 2600 outputs the video stream St83 to the video decoder3801. The video decoder 3801 thus detects the presentation timeinformation contained in the video stream St83, and disables the videooutput request signal St84 when the length of the received video streamSt83 is equivalent to the specified presentation time. A video streamequal in length to the specified presentation time is thus decoded bythe video decoder 3801, which outputs the reproduced video signal St95to the reordering buffer 3300 and selector 3400.

Because the encoded video stream is coded using the interframecorrelations between pictures, the coded order and display order do notnecessarily match on a frame unit basis. The video cannot, therefore, bedisplayed in the decoded order. The decoded frames are thereforetemporarily stored to the reordering buffer 3300. The synchronizer 2900therefore controls the switching signal St103 so that the reproducedvideo signal St95 output from the video decoder 3801 and the reorderingbuffer output St97 are appropriately selected and output in the displayorder to the synthesizer 3500.

The sub-picture decoder 3100 similarly generates the sub-picture outputrequest signal St86 based on the sub-picture decoding start signal St91,and outputs to the sub-picture buffer 2700. In response to thesub-picture output request signal St86, the sub-picture buffer 2700outputs the sub-picture stream St85 to the sub-picture decoder 3100.Based on the presentation time information contained in the sub-picturestream St85, the sub-picture decoder 3100 decodes a length of thesub-picture stream St85 corresponding to the specified presentation timeto reproduce and supply to the synthesizer 3500 the sub-picture signalSt99.

The synthesizer 3500 superimposes the selector 3400 output with thesub-picture signal St99 to generate and output the video signal St105 tothe video data output terminal 3600.

The audio decoder 3200 generates and supplies to the audio buffer 2800the audio output request signal St88 based on the audio stream decodingstart signal St93. The audio buffer 2800 thus outputs the audio streamSt87 to the audio decoder 3200. The audio decoder 3200 decodes a lengthof the audio stream St87 corresponding to the specified presentationtime based on the presentation time information contained in the audiostream St87, and outputs the decoded audio stream St101 to the audiodata output terminal 3700.

It is thus possible to reproduce a user-defined multimedia bitstream MBSin real-time according to a user-defined scenario. More specifically,each time the user selects a different scenario, the DVD decoder DCD isable to reproduce the title content desired by the user in the desiredsequence by reproducing the multimedia bitstream MBS corresponding tothe selected scenario.

It should be noted that the decoding system controller 2300 may supplythe title information signal St200 to the scenario selector 2100 bymeans of the infrared communications device mentioned above or anothermeans. Interactive scenario selection controlled by the user can also bemade possible by the scenario selector 2100 extracting the titleinformation recorded to the optical disk M from the file data structurearea FDS of the bitstream control data St63 contained in the titleinformation signal St200, and displaying this title information on adisplay for user selection.

Note, further, that the stream buffer 2400, video buffer 2600,sub-picture buffer 2700, audio buffer 2800, and reordering buffer 3300are expressed above and in the figures as separate entities because theyare functionally different. It will be obvious, however, that a singlebuffer memory can be controlled to provide the same discretefunctionality by time-share controlled use of a buffer memory with anoperating speed plural times faster than the read and write rates ofthese separate buffers.

Multi-Scene Control

The concept of multiple angle scene control according to the presentinvention is described below with reference to FIG. 21. As describedabove, titles that can be played back with numerous variations areconstructed from basic scene periods containing data common to eachtitle, and multi-scene periods comprising groups of different scenescorresponding to the various scenario requests. In FIG. 21, scenes 1, 5,and 8 are the common scenes of the basic scene periods. The multi-anglescenes (angles 1, 2, and 3) between scenes 1 and 5, and the parentallocked scenes (scenes 6 and 7) between scenes 5 and 8, are themulti-scene periods.

Scenes taken from different angles, i.e., angles 1, 2, and 3 in thisexample, can be dynamically selected and reproduced during playback inthe multi-angle scene period. In the parental locked scene period,however, only one of the available scenes, scenes 6 and 7, havingdifferent content can be selected, and must be selected staticallybefore playback begins.

Which of these scenes from the multi-scene periods is to be selected andreproduced is defined by the user operating the scenario selector 2100and thereby generating the scenario selection data St51. In scenario 1in FIG. 21 the user can freely select any of the multi-angle scenes, andscene 6 has been preselected for output in the parental locked sceneperiod. Similarly in scenario 2, the user can freely select any of themulti-angle scenes, and scene 7 has been preselected for output in theparental locked scene period.

With reference to FIGS. 30 and 31, furthermore, the contents of theprogram chain information VTS₋₋ PGCI is described. In FIG. 30, the casethat a scenario requested by the user is shown with respect to a VTSIdata construction. The scenario 1 and scenario 2 shown in FIG. 21 aredescribed as program chain information VTS₋₋ PGC#1 and VTS₋₋ PGC#2.VTS₋₋ PGC#1 describing the scenario 1 consists of cell playbackinformation C₋₋ PBI#1 corresponding to scene 1, C₋₋ PBI#2, C₋₋ PBI#3,and C₋₋ PBI#4 within a multi-angle cell block, C₋₋ PBI™5 correspondingto scene 5, C₋₋ PBI#6 corresponding to scene 6, and C₋₋ PBI#7corresponding to scene 8.

VTS₋₋ PGCI#2 describing the scenario 2 consists of cell playbackinformation C₋₋ PBI#1 corresponding to scene 1, C₋₋ PBI#2, C₋₋ PBI#3,and C₋₋ PBI#4 within a multi-angle cell block corresponding to amulti-angle scene, C₋₋ PBI#5 corresponding to scene 5, C₋₋ PBI#6corresponding to scene 7, and C₋₋ PBI#7 corresponding to scene 8.According to the digital video system data structure, a scene which is acontrol unit of a scenario is described as a cell which is a unitthereunder, thus a scenario requested by a user can be obtained.

In FIG. 31, the case that a scenario requested by the user shown in FIG.21 is shown with respect to a VOB data construction VTSTT₋₋ VOBS. Asspecifically shown in FIG. 31, the two scenarios 1 and 2 use the sameVOB data in common. With respect to a single scene commonly owned byeach scenario, VOB#1 corresponding to scene 1, VOB#5 corresponding toscene 5, and VOB#8 corresponding to scene 8 are arranged innon-interleaved block which is the contiguous block.

With respect to the multi-angle data commonly owned by scenarios 1 and2, one angle scene data is constructed by a single VOB. Specificallyspeaking, angle 1 constructed by VOB#2, and angle 2 is constructed byVOB#3, angle 3 is constructed by VOB#4. Thus constructed multi-angledata is formed as the interleaved block for the sake of switchingbetween each angle and seamless reproduction of each angle data. Scenes6 and 7 peculiar to scenarios 1 and 2, respectively, are formed as theinterleaved block for the sake of seamless reproduction between commonscenes before and behind thereof as well as seamless reproductionbetween each scene.

As described in the above, the user's requesting scenario shown in FIG.21 can be realized by utilizing the video title playback controlinformation shown in FIG. 30 and the title playback VOB data structureshown in FIG. 31.

Seamless Playback

The seamless playback capability briefly mentioned above with regard tothe digital video disk system data structure is described below. Notethat seamless playback refers to the reproduction in a digital videodisk system of multimedia data including video, audio, and sub-picturedata without intermittent breaks in the data or information betweenbasic scene periods, between basic scene periods and multi-sceneperiods, and between multi-scene periods.

Hardware factors contributing to intermittent playback of this data andtitle content include decoder underflow, i.e., an imbalance between thesource data input speed and the decoding speed of the input source data.

Other factors relate to the properties of the playback data. When theplayback data is data that must be continuously reproduced for aconstant time unit in order for the user to understand the content orinformation, e.g., audio data, data continuity is lost when the requiredcontinuous presentation time cannot be assured. Reproduction of suchinformation whereby the required continuity is assured is referred to as"contiguous information reproduction," or "seamless informationreproduction." Reproduction of this information when the requiredcontinuity cannot be assured is referred to as "non-continuousinformation reproduction," or "non-seamless information reproduction."It is obvious that continuous information reproduction andnon-continuous information reproduction are, respectively, seamless andnon-seamless reproduction.

Note that seamless reproduction can be further categorized as seamlessdata reproduction and seamless information reproduction. Seamless datareproduction is defined as preventing physical blanks or interruptionsin the data playback (intermittent reproduction) as a result of a bufferunderflow state, for example. Seamless information reproduction isdefined as preventing apparent interruptions in the information whenperceived by the user (intermittent presentation) when recognizinginformation from the playback data where there are no actual physicalbreaks in the data reproduction. The specific method enabling seamlessreproduction as thus described is described later below with referenceto FIGS. 23 and 24.

Interleaving

The DVD data system streams described above are recorded using anappropriate authoring encoder EC as a movie or other multimedia title ona DVD recording medium. Note that the following description refers to amovie as the multimedia title being processed, but it will be obviousthat the invention shall not be so limited.

Supplying a single movie in a format enabling the movie to be used inplural different cultural regions or countries requires the script to berecorded in the various languages used in those regions or countries. Itmay even necessitate editing the content to conform to the mores andmoral expectations of different cultures. Even using such alarge-capacity storage system as the DVD system, however, it isnecessary to reduce the bit rate, and therefore the image quality, ifplural full-length titles edited from a single common source title arerecorded to a single disk. This problem can be solved by recording thecommon parts of plural titles only once, and recording the segmentsdifferent in each title for each different title only. This method makesit possible to record plural titles for different countries or culturesto a single optical disk without reducing the bit rate, and, therefore,retaining high image quality.

As shown in FIG. 21, the titles recorded to a single optical diskcontain basic scene periods of scenes common to all scenarios, andmulti-scene periods containing scenes specific to certain scenarios, toprovide parental lock control and multi-angle scene control functions.

In the case of the parental lock control function, titles containing sexscenes, violent scenes, or other scenes deemed unsuitable for children,i.e., so-called "adult scenes," are recorded with a combination ofcommon scenes, adult scenes, and children's scenes. These title streamsare achieved by arraying the adult and children's scenes to multi-sceneperiods between the common basic scene periods.

Multi-angle control can be achieved in a conventional single-angle titleby recording plural multimedia scenes obtained by recording the subjectsfrom the desired plural camera angles to the multi-scene periods arrayedbetween the common basic scene periods. Note, however, that while theseplural scenes are described here as scenes recorded from differentcamera angles (positions), it will be obvious that the scenes may berecorded from the same camera angle but at different times, datagenerated by computer graphics, or other video data.

When data is shared between different scenarios of a single title, it isobviously necessary to move the laser beam LS from the common scene datato the non-common scene data during reproduction, i.e., to move theoptical pickup to a different position on the DVD recording medium RC1.The problem here is that the time required to move the optical pickupmakes it difficult to continue reproduction without creating breaks inthe audio or video, i.e., to sustain seamless reproduction. This problemcan be theoretically solved by providing a track buffer (stream buffer2400) to delay data output an amount equivalent to the worst accesstime. In general, data recorded to an optical disk is read by theoptical pickup, appropriately processed, and temporarily stored to thetrack buffer. The stored data is subsequently decoded and reproduced asvideo or audio data.

Definition of Interleaving

To thus enable the user to selectively excise scenes and choose fromamong plural scenes, a state wherein non-selected scene data is recordedinserted between common scene data and selective scene data necessarilyoccurs because the data units associated with individual scenes arecontiguously recorded to the recording tracks of the recording medium.If data is then read in the recorded sequence, non-selected scene datamust be accessed before accessing and decoding the selected scene data,and seamless connections with the selected scene is difficult. Theexcellent random access characteristics of the digital video disksystem, however, make seamless connections with the selected scenespossible.

In other words, by splitting scene-specific data into plural units of aspecified data size, and interleaving plural split data units fordifferent scenes in a predefined sequence that is recorded to diskwithin the jumping range whereby a data underflow state does not occur,it is possible to reproduce the selected scenes without datainterruptions by intermittently accessing and decoding the data specificto the selected scenes using these split data units. Seamless datareproduction is thereby assured.

Interleaved Block and Interleave Unit

The interleaving method enabling seamless data reproduction according tothe present invention is described below with reference to FIG. 24 andFIG. 54. Shown in FIG. 24 is a case from which three scenarios may bederived, i.e., branching from one video object VOB-A to one of pluralvideo objects VOB-B, VOB-C, and VOB-D, and then merging back again to asingle video object VOB-E. The actual arrangement of these blocksrecorded to a data recording track TR on disk is shown in FIG. 54.

Referring to FIG. 54, VOB-A and VOB-E are video objects with independentplayback start and end times, and are in principle arrayed to contiguousblock regions. As shown in FIG. 24, the playback start and end times ofVOB-B, VOB-C, and VOB-D are aligned during interleaving. The interleaveddata blocks are then recorded to disk to a contiguous interleaved blockregion. The contiguous block regions and interleaved block regions arethen written to disk in the track path Dr direction in the playbacksequence. Plural video objects VOB, i.e., interleaved video objectsVOBS, arrayed to the data recording track TR are shown in FIG. 54.

Referring to FIG. 54, data regions to which data is continuously arrayedare called "blocks," of which there are two types: "contiguous blockregions" in which VOB with discrete starting and end points arecontiguously arrayed, and "interleaved block regions" in which pluralVOB with aligned starting and end points are interleaved. The respectiveblocks are arrayed as shown in FIG. 55 in the playback sequence, i.e.,block 1, block 2, block 3, . . . block 7.

As shown in FIG. 55, the VTS title VOBS (VTSTT₋₋ VOBS) consist of blocks1-7, inclusive. Block 1 contains VOB 1 alone. Blocks 2, 3, 5, and 7similarly discretely contain VOBS 2, 3, 6, and 10. Blocks 2, 3, 5, and 7are thus contiguous block regions.

Block 4, however, contains VOB 4 and VOB 5 interleaved together, whileblock 6 contains VOB 7, VOB 8, and VOB 9 interleaved together. Blocks 4and 6 are thus interleaved block regions.

The internal data structure of the contiguous block regions is shown inFIG. 56 with VOB-i and VOB-j arrayed as the contiguous blocks in theVOBs. As described with reference to FIG. 16, VOB-i and VOB-j inside thecontiguous block regions are further logically divided into cells as theplayback unit. Both VOB-i and VOB-j in this figure are shown comprisingthree cells CELL #1, CELL #2, and CELL #3.

Each cell comprises one or more video object unit VOBU with the videoobject unit VOBU defining the boundaries of the cell. Each cell alsocontains information identifying the position of the cell in the programchain PGC (the playback control information of the digital video disksystem). More specifically, this position information is the address ofthe first and last VOBU in the cell. As also shown in FIG. 56, these VOBand the cells defined therein are also recorded to a contiguous blockregion so that contiguous blocks are contiguously reproduced.Reproducing these contiguous blocks is therefore no problem.

The internal data structure of the interleaved block regions is shown inFIG. 57. In the interleaved block regions each video object VOB isdivided into interleaved units ILVU, and the interleaved units ILVUassociated with each VOB are alternately arrayed. Cell boundaries aredefined independently of the interleaved units ILVU. For example, VOB-kis divided into four interleaved units ILVUk1, ILVUk2, ILVUk3, andILVUk4, and are confined by a single cell CELL#k. VOB-k is likewisedivided into four interleaved units ILVUm1, ILVUm2, ILVUm3, and ILVUm4,and is confined by a single cell CELL#m. Note that instead of a singlecell CELL#k or CELL#m, each of VOB-k and VOB-m can be divided into morethan two cells. The interleaved units ILVU thus contains both audio andvideo data.

In the example shown in FIG. 57, the interleaved units ILVUk1, ILVUk2,ILVUk3, and ILVUk4, and ILVUm1, ILVUm2, ILVUm3, and ILVUm4, from twodifferent video objects VOB-k and VOB-m are alternately arrayed within asingle interleaved block. By interleaving the interleaved units ILVU oftwo video objects VOB in this sequence, it is possible to achieveseamless reproduction branching from one scene to one of plural scenes,and from one of plural scenes to one scene.

Multi-Scene Control

The multi-scene period is described together with the concept ofmulti-scene control according to the present invention using by way ofexample a title comprising scenes recorded from different angles.

Each scene in multi-scene control is recorded from the same angle, butmay be recorded at different times or may even be computer graphicsdata. The multi-angle scene periods may therefore also be calledmulti-scene periods.

Parental Control

The concept of recording plural titles comprising alternative scenes forsuch functions as parental lock control and recording director's cuts isdescribed below using FIG. 15.

An example of a multi-rated title stream providing for parental lockcontrol is shown in FIG. 15. When so-called "adult scenes" containingsex, violence, or other scenes deemed unsuitable for children arecontained in a title implementing parental lock control, the titlestream is recorded with a combination of common system streams SSa, SSb,and Sse, an adult-oriented system stream SSc containing the adultscenes, and a child-oriented system stream SSd containing only thescenes suitable for children. Title streams such as this are recorded asa multi-scene system stream containing the adult-oriented system streamSsc and the child-oriented system stream Ssd arrayed to the multi-sceneperiod between common system streams Ssb and Sse.

The relationship between each of the component titles and the systemstream recorded to the program chain PGC of a title stream thuscomprised is described below.

The adult-oriented title program chain PGC1 comprises in sequence thecommon system streams Ssa and Ssb, the adult-oriented system stream Ssc,and the common system stream Sse. The child-oriented title program chainPGC2 comprises in sequence the common system streams Ssa and Ssb, thechild-oriented system stream Ssd, and the common system stream Sse.

By thus arraying the adult-oriented system stream Ssc and child-orientedsystem stream Ssd to a multi-scene period, the decoding methodpreviously described can reproduce the title containing adult-orientedcontent by reproducing the common system streams Ssa and Ssb, thenselecting and reproducing the adult-oriented system stream Ssc, and thenreproducing the common system stream Sse as instructed by theadult-oriented title program chain PGC1. By alternatively following thechild-oriented title program chain PGC2 and selecting the child-orientedsystem stream Ssd in the multi-scene period, a child-oriented title fromwhich the adult-oriented scenes have been expurgated can be reproduced.

This method of providing in the title stream a multi-scene periodcontaining plural alternative scenes, selecting which of the scenes inthe multi-scene period are to be reproduced before playback begins, andgenerating plural titles containing essentially the same title contentbut different scenes in part, is called parental lock control.

Note that parental lock control is so named because of the perceivedneed to protect children from undesirable content. From the perspectiveof system stream processing, however, parental lock control is atechnology for statically generating different title streams by means ofthe user pre-selecting specific scenes from a multi-scene period. Note,further, that this contrasts with multi-angle scene control, which is atechnology for dynamically changing the content of a single title bymeans of the user selecting scenes from the multi-scene period freelyand in real-time during title playback.

This parental lock control technology can also be used to enable titlestream editing such as when making the director's cut. The director'scut refers to the process of editing certain scenes from a movie to, forexample, shorten the total presentation time. This may be necessary, forexample, to edit a feature-length movie for viewing on an airplane wherethe presentation time is too long for viewing within the flight time orcertain content may not be acceptable. The movie director thusdetermines which scenes may be cut to shorten the movie. The title canthen be recorded with both a full-length, unedited system stream and anedited system stream in which the edited scenes are recorded tomulti-scene periods. At the transition from one system stream to anothersystem stream in such applications, parental lock control must be ableto maintain smooth playback image output. More specifically, seamlessdata reproduction whereby a data underflow state does not occur in theaudio, video, or other buffers, and seamless information reproductionwhereby no unnatural interruptions are audibly or visibly perceived inthe audio and video playback, are necessary.

Multi-Angle Control

The concept of multi-angle scene control in the present invention isdescribed next with reference to FIG. 33. In general, multimedia titlesare obtained by recording both the audio and video information(collectively "recording" below) of the subject over tine T. The angledscene blocks #SC1, #SM1, #SM2, #SM3, and #SC3 represent the multimediascenes obtained at recording unit times T1, T2, and T3 by recording thesubject at respective camera angles. Scenes #SM1, #SM2, and #SM3 arerecorded at mutually different (first, second, and third) camera anglesduring recording unit time T2, and are referenced below as the first,second, and third angled scenes.

Note that the multi-scene periods referenced herein are basicallyassumed to comprise scenes recorded from different angles. The scenesmay, however, be recorded from the same angle but at different times, orthey may be computer graphics data. The multi-angle scene periods arethus the multi-scene periods from which plural scenes can be selectedfor presentation in the same time period, whether or not the scenes areactually recorded at different camera angles.

Scenes #SC1 and #SC3 are scenes recorded at the same common camera angleduring recording unit times Ti and T3, i.e., before and after themulti-angle scenes. These scenes are therefore called "common anglescenes." Note that one of the multiple camera angles used in themulti-angle scenes is usually the same as the common camera angle.

To understand the relationship between these various angled scenes,multi-angle scene control is described below using a live broadcast of abaseball game for example only.

The common angle scenes #SC1 and #SC3 are recorded at the common cameraangle, which is here defined as the view from center field on the axisthrough the pitcher, batter, and catcher.

The first angled scene #SM1 is recorded at the first multi-camera angle,i.e., the camera angle from the backstop on the axis through thecatcher, pitcher, and batter. The second angled scene #SM2 is recordedat the second multi-camera angle, i.e., the view from center field onthe axis through the pitcher, batter, and catcher. Note that the secondangled scene #SM2 is thus the same as the common camera angle in thisexample. It therefore follows that the second angled scene #SM2 is thesame as the common angle scene ISC2 recorded during recording unit timeT2. The third angled scene #SM3 is recorded at the third multi-cameraangle, i.e., the camera angle from the backstop focusing on the infield.

The presentation times of the multiple angle scenes #SM1, #SM2, and #SM3overlap in recording unit time T2; this period is called the"multi-angle scene period." By freely selecting one of the multipleangle scenes #SM1, #SM2, and #SM3 in this multi-angle scene period, theviewer is able to change his or her virtual viewing position to enjoy adifferent view of the game as though the actual camera angle is changed.Note that while there appears to be a time gap between common anglescenes #SC1 and #SC3 and the multiple angle scenes #SM1, #SM2, and #SM3in FIG. 33, this is simply to facilitate the use of arrows in the figurefor easier description of the data reproduction paths reproduced byselecting different angled scenes. There is no actual time gap duringplayback.

Multi-angle scene control of the system stream based on the presentinvention is described next with reference to FIG. 23 from theperspective of connecting data blocks. The multimedia data correspondingto common angle scene ISC is referenced as common angle data BA, and thecommon angle data BA in recording unit times T1 and T3 are referenced asBA1 and BA3, respectively. The multimedia data corresponding to themultiple angle scenes #SM1, #SM2, and #SM3 are referenced as first,second, and third angle scene data MA1, MA2, and MA3. As previouslydescribed with reference to FIG. 33, scenes from the desired angled canbe viewed by selecting one of the multiple angle data units MA1, MA2,and MA3. There is also no time gap between the common angle data BA1 andBA3 and the multiple angle data units MA1, MA2, and MA3.

In the case of an MPEG system stream, however, intermittent breaks inthe playback information can result between the reproduced common andmultiple angle data units depending upon the content of the data at theconnection between the selected multiple angle data unit MA1, MA2, andMA3 and the common angle data BA (either the first common angle data BA1before the angle selected in the multi-angle scene period or the commonangle data BA3 following the angle selected in the multi-angle sceneperiod). The result in this case is that the title stream is notnaturally reproduced as a single contiguous title, i.e., seamless datareproduction is achieved but non-seamless information reproductionresults.

The multi-angle selection process whereby one of plural scenes isselectively reproduced from the multi-angle scene period with seamlessinformation presentation to the scenes before and after is describedbelow with application in a digital video disk system using FIG. 23.

Changing the scene angle, i.e., selecting one of the multiple angle dataunits MA1, MA2, and MA3, must be completed before reproduction of thepreceding common angle data BA1 is completed. It is extremely difficult,for example, to change to a different angle data unit MA2 duringreproduction of common angle data BA1. This is because the multimediadata has a variable length coded MPEG data structure, which makes itdifficult to find the data break points (boundaries) in the selecteddata blocks. The video may also be disrupted when the angle is changedbecause inter-frame correlations are used in the coding process. Thegroup₋₋ of₋₋ pictures GOP processing unit of the MPEG standard containsat least one refresh frame, and closed processing not referencing framesbelonging to another GOP is possible within this GOP processing unit.

In other words, if the desired angle data, e.g., MA3, is selected beforereproduction reaches the multi-angle scene period, and at the latest bythe time reproduction of the preceding common angle data BA1 iscompleted, the angle data selected from within the multi-angle sceneperiod can be seamlessly reproduced. However, it is extremely difficultwhile reproducing one angle to select and seamlessly reproduce anotherangle within the same multi-angle scene period. It is thereforedifficult when in a multi-angle scene period to dynamically select adifferent angle unit presenting, for example, a view from a differentcamera angle.

Flow Chart: Encoder

The encoding information table generated by the encoding systemcontroller 200 from information extracted from the scenario data St7 isdescribed below referring to FIG. 27.

The encoding information table contains VOB set data streams containingplural VOB corresponding to the scene periods beginning and ending atthe scene branching and connecting points, and VOB data streamscorresponding to each scene. These VOB set data streams shown in FIG. 27are the encoding information tables generated at step #100 in FIG. 34 bythe encoding system controller 200 for creating the DVD multimediastream based on the user-defined title content.

The user-defined scenario contains branching points from common scenesto plural scenes, or connection points to other common scenes. The VOBcorresponding to the scene period delimited by these branching andconnecting points is a VOB set, and the data generated to encode a VOBset is the VOB set data stream. The title number specified by the VOBset data stream is the title number TITLE₋₋ NO of the VOB set datastream.

The VOB Set data structure in FIG. 27 shows the data content forencoding one VOB set in the VOB set data stream, and comprises: the VOBset number VOBS₋₋ NO, the VOB number VOB₋₋ NO in the VOB set, thepreceding VOB seamless connection flag VOB₋₋ Fsb, the following VOBseamless connection flag VOB₋₋ Fsf, the multi-scene flag VOB₋₋ Fp, theinterleave flag VOB₋₋ Fi, the multi-angle flag VOB₋₋ Fm, the multi-angleseamless switching flag VOB₋₋ FsV, the maximum bit rate of theinterleaved VOB ILV₋₋ BR, the number of interleaved VOB divisions ILV₋₋DIV, and the minimum interleaved unit presentation time ILVU_(--MT).

The VOB set number VOBS₋₋ NO is a sequential number identifying the VOBset and the position of the VOB set in the reproduction sequence of thetitle scenario.

The VOB number VOB₋₋ NO is a sequential number identifying the VOB andthe position of the VOB in the reproduction sequence of the titlescenario.

The preceding VOB seamless connection flag VOB₋₋ Fsb indicates whether aseamless connection with the preceding VOB is required for scenarioreproduction.

The following VOB seamless connection flag VOB₋₋ Fsf indicates whetherthere is a seamless connection with the following VOB during scenarioreproduction.

The multi-scene flag VOB₋₋ Fp identifies whether the VOB set comprisesplural video objects VOB.

The interleave flag VOB₋₋ Fi identifies whether the VOB in the VOB setare interleaved.

The multi-angle flag VOB₋₋ Fm identifies whether the VOB set is amulti-angle set.

The multi-angle seamless switching flag VOB₋₋ FsV identifies whetherangle changes within the multi-angle scene period are seamless or not.

The maximum bit rate of the interleaved VOB ILV₋₋ BR defines the maximumbit rate of the interleaved VOBs.

The number of interleaved VOB divisions ILV₋₋ DIV identifies the numberof interleave units in the interleaved VOB.

The minimum interleave unit presentation tine ILVU₋₋ MT defines the timethat can be reproduced when the bit rate of the smallest interleave unitat which a track buffer data underflow state does not occur is themaximum bit rate of the interleaved VOB ILV₋₋ BR during interleavedblock reproduction.

The encoding information table for each VOB generated by the encodingsystem controller 200 based on the scenario data St7 is described belowreferring to FIG. 28. The VOB encoding parameters described below andsupplied to the video encoder 300, audio encoder 700, and system encoder900 for stream encoding are produced based on this encoding informationtable.

The VOB data streams shown in FIG. 28 are the encoding informationtables generated at step #100 in FIG. 34 by the encoding systemcontroller 200 for creating the DVD multimedia stream based on theuser-defined title content.

The encoding unit is the video object VOB, and the data generated toencode each video object VOB is the VOB data stream. For example, a VOBset comprising three angle scenes comprises three video objects VOB. Thedata structure shown in FIG. 28 shows the content of the data forencoding one VOB in the VOB data stream.

The VOB data structure contains the video material start time VOB₋₋ VST,the video material end time VOB₋₋ VEND, the video signal type VOB₋₋ V₋₋KIND, the video encoding bit rate V₋₋ BR, the audio material start timeVOB₋₋ AST, the audio material end time VOB₋₋ AEND, the audio codingmethod VOB₋₋ A₋₋ KIND, and the audio encoding bit rate A₋₋ BR.

The video material start time VOB₋₋ VST is the video encoding start timecorresponding to the time of the video signal.

The video material end time VOB₋₋ VEND is the video encoding end timecorresponding to the tine of the video signal.

The video material type VOB₋₋ V₋₋ KIND identifies whether the encodedmaterial is in the NTSC or PAL format, for example, or is photographicmaterial (a movie, for example) converted to a television broadcastformat (so-called telecine conversion).

The video encoding bit rate V₋₋ BR is the bit rate at which the videosignal is encoded.

The audio material start time VOB₋₋ AST is the audio encoding start timecorresponding to the time of the audio signal.

The audio material end time VOB₋₋ AEND is the audio encoding end timecorresponding to the time of the audio signal.

The audio coding method VOB₋₋ A₋₋ KIND identifies the audio encodingmethod as AC-3, MPEG, or linear PCM, for example.

The audio encoding bit rate A₋₋ BR is the bit rate at which the audiosignal is encoded.

The encoding parameters used by the video encoder 300, sub-pictureencoder 500, and audio encoder 700, and system encoder 900 for VOBencoding are shown in FIG. 29. The encoding parameters include: the VOBnumber VOB₋₋ NO, video encode start time V₋₋ STTM, video encode end timeV₋₋ ENDTM, the video encode mode V₋₋ ENCMD, the video encode bit rateV₋₋ RATE, the maximum video encode bit rate V₋₋ MRATE, the GOP structurefixing flag GOP₋₋ Fxflag, the video encode GOP structure GOPST, theinitial video encode data V₋₋ INTST, the last video encode data V₋₋ENDST, the audio encode start time A₋₋ STTM, the audio encode end timeA₋₋ ENDTM, the audio encode bit rate A₋₋ RATE, the audio encode methodA₋₋ ENCMD, the audio start gap A₋₋ STGAP, the audio end gap A₋₋ ENDGAP,the preceding VOB number B₋₋ VOB₋₋ NO, and the following VOB number F₋₋VOB₋₋ NO.

The VOB number VOB₋₋ NO is a sequential number identifying the VOB andthe position of the VOB in the reproduction sequence of the titlescenario.

The video encode start time V₋₋ STTM is the start time of video materialencoding.

The video encode end time V₋₋ ENDTM is the end time of video materialencoding.

The video encode mode V₋₋ ENCMD is an encoding mode for declaringwhether reverse telecine conversion shall be accomplished during videoencoding to enable efficient coding when the video material is telecineconverted material.

The video encode bit rate V₋₋ RATE is the average bit rate of videoencoding.

The maximum video encode bit rate V₋₋ MRATE is the maximum bit rate ofvideo encoding.

The GOP structure fixing flag GOP₋₋ Fxflag specifies whether encoding isaccomplished without changing the GOP structure in the middle of thevideo encoding process. This is a useful parameter for declaring whetherseamless switch is enabled in a multi-angle scene period.

The video encode GOP structure GOPST is the GOP structure data fromencoding.

The initial video encode data V₋₋ INTST sets the initial value of theVBV buffer (decoder buffer) at the start of video encoding, and isreferenced during video decoding to initialize the decoding buffer. Thisis a useful parameter for declaring seamless reproduction with thepreceding encoded video stream.

The last video encode data V₋₋ ENDST sets the end value of the VBVbuffer (decoder buffer) at the end of video encoding, and is referencedduring video decoding to initialize the decoding buffer. This is auseful parameter for declaring seamless reproduction with the precedingencoded video stream.

The audio encode start time A₋₋ STTM is the start time of audio materialencoding.

The audio encode end time A₋₋ ENDTM is the end time of audio materialencoding.

The audio encode bit rate A₋₋ RATE is the bit rate used for audioencoding.

The audio encode method A₋₋ ENCMD identifies the audio encoding methodas AC-3, MPEG, or linear PCM, for example.

The audio start gap A₋₋ STGAP is the time offset between the start ofthe audio and video presentation at the beginning of a VOB. This is auseful parameter for declaring seamless reproduction with the precedingencoded system stream.

The audio end gap A₋₋ ENDGAP is the time offset between the end of theaudio and video presentation at the end of a VOB. This is a usefulparameter for declaring seamless reproduction with the preceding encodedsystem stream.

The preceding VOB number B₋₋ VOB₋₋ NO is the VOB₋₋ NO of the precedingVOB when there is a seamlessly connected preceding VOB.

The following VOB number F₋₋ VOB₋₋ NO is the VOB₋₋ NO of the followingVOB when there is a seamlessly connected following VOB.

The operation of a DVD encoder ECD according to the present invention isdescribed below with reference to the flow chart in FIG. 34. Note thatthe steps shown with a double line are subroutines. It should be obviousthat while the operation described below relates specifically in thiscase to the DVD encoder ECD of the present invention, the operationdescribed also applies to an authoring encoder EC.

At step #100, the user inputs the editing commands according to theuser-defined scenario while confirming the content of the multimediasource data streams St1, St2, and St3.

At step #200, the scenario editor 100 generates the scenario data St7containing the above edit command information according to the user'sediting instructions.

When generating the scenario data St7 in step #200, the user editingcommands related to multi-angle and parental lock multi-scene periods inwhich interleaving is presumed must be input to satisfy the followingconditions.

First, the VOB maximum bit rate must be set to assure sufficient imagequality, and the track buffer capacity, jump performance, jump time, andjump distance of the DVD decoder DCD used as the reproduction apparatusof the DVD encoded data must be determined. Based on these values, thereproduction time of the shortest interleaved unit is obtained fromequations 3 and 4. Based on the reproduction time of each scene in themulti-scene period, it must then be determined whether equations 5 and 6are satisfied. If equations 5 and 6 are not satisfied, the user mustchange the edit commands until equations 5 and 6 are satisfied by, forexample, connecting part of the following scene to each scene in themulti-scene period.

When multi-angle edit commands are used, equation 7 must be satisfiedfor seamless switching, and edit commands matching the audioreproduction time with the reproduction time of each scene in each anglemust be entered. If non-seamless switching is used, the user must entercommands to satisfy equation 8.

At step #300, the encoding system controller 200 first determineswhether the target scene is to be seamlessly connected to the precedingscene based on the scenario data St7.

Note that when the preceding scene period is a multi-scene periodcomprising plural scenes but the presently selected target scene is acommon scene (not in a multi-scene period), a seamless connection refersto seamlessly connecting the target scene with any one of the scenescontained in the preceding multi-scene period. When the target scene isa multi-scene period, a seamless connection still refers to seamlesslyconnecting the target scene with any one of the scenes from the samemulti-scene period.

If step #300 returns NO, i.e., a non-seamless connection is valid, theprocedure moves to step #400.

At step #400, the encoding system controller 200 resets the precedingVOB seamless connection flag VOB₋₋ Fsb indicating whether there is aseamless connection between the target and preceding scenes. Theprocedure then moves to step #600.

On the other hand, if step #300 returns YES, i.e., there is a seamlessconnection to the preceding scene, the procedure moves to step #500.

At step #500 the encoding system controller 200 sets the preceding VOBseamless connection flag VOB₋₋ Fsb. The procedure then moves to step#600.

At step #600 the encoding system controller 200 determines whether thereis a seamless connection between the target and following scenes basedon scenario data St7. If step #600 returns NO, i.e., a non-seamlessconnection is valid, the procedure moves to step #700.

At step #700, the encoding system controller 200 resets the followingVOB seamless connection flag VOB₋₋ Fsf indicating whether there is aseamless connection with the following scene. The procedure then movesto step #900.

However, if step #600 returns YES, i.e., there is a seamless connectionto the following scene, the procedure moves to step #800.

At step #800 the encoding system controller 200 sets the following VOBseamless connection flag VOB₋₋ Fsf. The procedure then moves to step#900.

At step #900 the encoding system controller 200 determines whether thereis more than connection target scene, i.e., whether a multi-scene periodis selected, based on the scenario data St7. As previously described,there are two possible control methods in multi-scene periods: parentallock control whereby only one of plural possible reproduction paths thatcan be constructed from the scenes in the multi-scene period isreproduced, and multi-angle control whereby the reproduction path can beswitched within the multi-scene period to present different viewingangles.

If step #900 returns NO, i.e., there are not multiple scenes, theprocedure moves to step #1000.

At step #1000 the multi-scene flag VOB₋₋ Fp identifying whether the VOBset comprises plural video objects VOB (a multi-scene period isselected) is reset, and the procedure moves to step #1800 for encodeparameter production. This encode parameter production subroutine isdescribed below.

However, if step #900 returns YES, there is a multi-scene connection,the procedure moves to step #1100.

At step #1100, the multi-scene flag VOB₋₋ Fp is set, and the proceduremoves to step #1200 whereat it is judged whether a multi-angleconnection is selected, or not.

At step #1200 it is determined whether a change is made between pluralscenes in the multi-scene period, i.e., whether a multi-angle sceneperiod is selected. If step #1200 returns NO, i.e., no scene change isallowed in the multi-scene period as parental lock control reproducingonly one reproduction path has been selected, the procedure moves tostep #1300.

At step #1300 the multi-angle flag VOB₋₋ FM identifying whether thetarget connection scene is a multi-angle scene is reset, and theprocedure moves to step #1302.

At step #1302 it is determined whether either the preceding VOB seamlessconnection flag VOB₋₋ Fsb or following VOB seamless connection flagVOB₋₋ Fsf is set. If step #1302 returns YES, i.e., the target connectionscene seamlessly connects to the preceding, the following, or both thepreceding and following scenes, the procedure moves to step #1304.

At step #1304 the interleave flag VOB₋₋ Fi identifying whether the VOB,the encoded data of the target scene, is interleaved is set. Theprocedure then moves to step #1800.

However, if step #1302 returns NO, i.e., the target connection scenedoes not seamlessly connect to the preceding or following scene, theprocedure moves to step #1306.

At step #1306 the interleave flag VOB₋₋ Fi is reset, and the proceduremoves to step #1800.

If step #1200 returns YES, however, i.e., there is a multi-angleconnection, the procedure moves to step #1400.

At step #1400, the multi-angle flag VOB₋₋ FM and interleave flag VOB₋₋Fi are set, and the procedure moves to step #1500.

At step #1500 the encoding system controller 200 determines whether theaudio and video can be seamlessly switched in a multi-angle sceneperiod, i.e., at a reproduction unit smaller than the VOB, based on thescenario data St7. If step #1500 returns NO, i.e., non-seamlessswitching occurs, the procedure moves to step #1600.

At step #1600 the multi-angle seamless switching flag VOB₋₋ FsVindicating whether angle changes within the multi-angle scene period areseamless or not is reset, and the procedure moves to step #1800.

However, if step #1500 returns YES, i.e., seamless switching occurs, theprocedure moves to step #1700.

At step #1700 the multi-angle seamless switching flag VOB₋₋ FSV is set,and the procedure moves to step #1800.

Therefore, as shown by the flow chart in FIG. 34, encode parameterproduction (step #1800) is only begun after the editing information isdetected from the above flag settings in the scenario data St7reflecting the user-defined editing instructions.

Based on the user-defined editing instructions detected from the aboveflag settings in the scenario data St7, information is added to theencoding information tables for the VOB Set units and VOB units as shownin FIGS. 27 and 28 to encode the source streams, and the encodingparameters of the VOB data units shown in FIG. 29 are produced, in step#1800. The procedure then moves to step #1900 for audio and videoencoding.

The encode parameter production steps (step #1800) are described ingreater detail below referring to FIGS. 35, 36, 37, and 38.

Based on the encode parameters produced in step #1800, the video dataand audio data are encoded in step #1900, and the procedure moves tostep #2000.

Note that the sub-picture data is normally inserted during videoreproduction on an as-needed basis, and contiguity with the precedingand following scenes is therefore not usually necessary. Moreover, thesub-picture data is normally video information for one frame, and unlikeaudio and video data having an extended time-base, sub-picture data isusually static, and is not normally presented continuously. Because thepresent invention relates specifically to seamless and non-seamlesscontiguous reproduction as described above, description of sub-picturedata encoding is omitted herein for simplicity.

Step #2000 is the last step in a loop comprising steps #300 to step#2000, and causes this loop to be repeated as many times as there areVOB Sets. This loop formats the program chain VTS₋₋ PGC#i to contain thereproduction sequence and other reproduction information for each VOB inthe title (FIG. 16) in the program chain data structure, interleaves theVOB in the multi-scene periods, and completes the VOB Set data streamand VOB data stream needed for system stream encoding. The procedurethen moves to step #2100.

At step #2100 the VOB Set data stream is completed as the encodinginformation table by adding the total number of VOB Sets VOBS₋₋ NUMobtained as a result of the loop through step #2000 to the VOB Set datastream, and setting the number of titles TITLE₋₋ NO defining the numberof scenario reproduction paths in the scenario data St7. The procedurethen moves to step #2200.

System stream encoding producing the VOB (VOB#i) data in the VTS titleVOBS (VTSTT₋₋ VOBS) (FIG. 16) is accomplished in step #2200 based on theencoded video stream and encoded audio stream output from step #1900,and the encode parameters in FIG. 29. The procedure then moves to step#2300.

At step #2300 the VTS information VTSI, VTSI management table VTSI₋₋MAT, VTSPGC information table VTS₋₋ PGCIT, and the program chaininformation VTS₋₋ PGCI#i controlling the VOB data reproduction sequenceshown in FIG. 16 are produced, and formatting to, for example,interleave the VOB contained in the multi-scene periods, isaccomplished.

The encode parameter production subroutine shown as step #1800 in FIG.34B is described next using FIGS. 35, 36, and 37 using by way of examplethe operation generating the encode parameters for multi-angle control.

Starting from FIG. 35, the process for generating the encode parametersof a non-seamless switching stream with multi-angle control is describedfirst. This stream is generated when step #1500 in FIG. 34 returns NOand the following flags are set as shown: VOB₋₋ Fsb-1 or VOB₋₋ Fsf=1,VOB₋₋ Fp=1, VOB₋₋ Fi=1, VOB₋₋ Fm=1, and VOB₋₋ FsV=0. The followingoperation produces the encoding information tables shown in FIG. 27 andFIG. 28, and the encode parameters shown in FIG. 29.

At step #1812, the scenario reproduction sequence (path) contained inthe scenario data St7 is extracted, the VOB Set number VOBS₋₋ NO is set,and the VOB number VOB₋₋ NO is set for one or more VOB in the VOB Set.

At step #1814 the maximum bit rate ILV₋₋ BR of the interleaved VOB isextracted from the scenario data St7, and the maximum video encode bitrate V₋₋ MRATE from the encode parameters is set based on the interleaveflag VOB₋₋ Fi setting (=1).

At step #1816, the minimum interleaved unit presentation time ILVU₋₋ MTis extracted from the scenario data St7.

At step #1818, the video encode GOP structure GOPST values N=15 and M=3are set, and the GOP structure fixing flag GOP₋₋ Fxflag is set (=1),based on the multi-scene flag VOB₋₋ Fp setting (=1).

Step #1820 is the common VOB data setting routine, which is describedbelow referring to the flow chart in FIG. 36. This common VOB datasetting routine produces the encoding information tables shown in FIGS.27 and 28, and the encode parameters shown in FIG. 29.

At step #1822 the video material start time VOB₋₋ VST and video materialend time VOB₋₋ VEND are extracted for each VOB, and the video encodestart time V₋₋ STTM and video encode end time V₋₋ ENDTM are used asvideo encoding parameters.

At step #1824 the audio material start time VOB₋₋ AST of each VOB isextracted from the scenario data St7, and the audio encode start timeA₋₋ STTM is set as an audio encoding parameter.

At step #1826 the audio material end time VOB₋₋ AEND is extracted foreach VOB from the scenario data St7, and at a time not exceeding theVOB₋₋ AEND time. This time extracted at an audio access unit (AAU) isset as the audio encode end time A₋₋ ENDTM which is an audio encodingparameter. Note that the audio access unit AAU is determined by theaudio encoding method.

At step #1828 the audio start gap A₋₋ STGAP obtained from the differencebetween the video encode start time V₋₋ STTM and the audio encode starttime A₋₋ STTM is defined as a system encode parameter.

At step #1830 the audio end gap A₋₋ ENDGAP obtained from the differencebetween the video encode end time V₋₋ ENDTM and the audio encode endtime A₋₋ ENDTM is defined as a system encode parameter.

At step #1832 the video encoding bit rate V₋₋ BR is extracted from thescenario data St7, and the video encode bit rate V₋₋ RATE, which is theaverage bit rate of video encoding, is set as a video encodingparameter.

At step #1834 the audio encoding bit rate A₋₋ BR is extracted from thescenario data St7, and the audio encode bit rate A₋₋ RATE is set as anaudio encoding parameter.

At step #1836 the video material type VOB₋₋ V₋₋ KIND is extracted fromthe scenario data St7. If the material is a film type, i.e., a movieconverted to television broadcast format (so-called telecineconversion), reverse telecine conversion is set for the video encodemode V₋₋ ENCMD, and defined as a video encoding parameter.

At step #1838 the audio coding method VOB₋₋ A₋₋ KIND is extracted fromthe scenario data St7, and the encoding method is set as the audioencode method A₋₋ ENCMD and set as an audio encoding parameter.

At step #1840 the initial video encode data V₋₋ INTST sets the initialvalue of the VBV buffer to a value less than the VBV buffer end valueset by the last video encode data V₋₋ ENDST, and defined as a videoencoding parameter.

At step #1842 the VOB number VOB₋₋ NO of the preceding connection is setto the preceding VOB number B₋₋ VOB₋₋ NO based on the setting (=1) ofthe preceding VOB seamless connection flag VOB₋₋ Fsb, and set as asystem encode parameter.

At step #1844 the VOB number VOB₋₋ NO of the following connection is setto the following VOB number F₋₋ VOB₋₋ NO based on the setting (=1) ofthe following VOB seamless connection flag VOB₋₋ Fsf, and set as asystem encode parameter.

The encoding information table and encode parameters are thus generatedfor a multi-angle VOB Set with non-seamless multi-angle switchingcontrol enabled.

The process for generating the encode parameters of a seamless switchingstream with multi-angle control is described below with reference toFIG. 37. This stream is generated when step #1500 in FIG. 34 returns YESand the following flags are set as shown: VOB₋₋ Fsb=1 or VOB₋₋ Fsf=1,VOB₋₋ Fp=1, VOB₋₋ Fi=1, VOB₋₋ Fm=1, and VOB₋₋ FsV=1. The followingoperation produces the encoding information tables shown in FIG. 27 andFIG. 28, and the encode parameters shown in FIG. 29.

The following operation produces the encoding information tables shownin FIG. 27 and FIG. 28, and the encode parameters shown in FIG. 29.

At step #1850, the scenario reproduction sequence (path) contained inthe scenario data St7 is extracted, the VOB Set number VOBS₋₋ NO is set,and the VOB number VOB₋₋ NO is set for one or more VOB in the VOB Set.

At step #1852 the maximum bit rate ILV₋₋ BR of the interleaved VOB isextracted from the scenario data St7, and the maximum video encode bitrate V₋₋ MRATE from the encode parameters is set based on the interleaveflag VOB₋₋ Fi setting (=1).

At step #1854, the minimum interleaved unit presentation time ILVU₋₋ MTis extracted from the scenario data St7.

At step #1856, the video encode GOP structure GOPST values N=15 and M=3are set, and the GOP structure fixing flag GOP₋₋ Fxflag is set (=1),based on the multi-scene flag VOB₋₋ Fp setting (=1).

At step #1858, the video encode GOP GOPST is set to "closed GOP" basedon the multi-angle seamless switching flag VOB₋₋ FsV setting (=1), andthe video encoding parameters are thus defined.

Step #1860 is the common VOB data setting routine, which is as describedreferring to the flow chart in FIG. 35. Further description thereof isthus omitted here.

The encode parameters of a seamless switching stream with multi-anglecontrol are thus defined for a VOB Set with multi-angle control asdescribed above.

The process for generating the encode parameters for a system stream inwhich parental lock control is implemented is described below withreference to FIG. 38. This stream is generated when step #1200 in FIG.34 returns NO and step #1304 returns YES, i.e., the following flags areset as shown: VOB₋₋ Fsb=1 or VOB₋₋ Fsf=1, VOB₋₋ Fp=1, VOB₋₋ Fi=1, VOB₋₋Fm=0. The following operation produces the encoding information tablesshown in FIG. 27 and FIG. 28, and the encode parameters shown in FIG.29.

At step #1870, the scenario reproduction sequence (path) contained inthe scenario data St7 is extracted, the VOB Set number VOBS₋₋ NO is set,and the VOB number VOB₋₋ NO is set for one or more VOB in the VOB Set.

At step #1872 the maximum bit rate ILV₋₋ BR of the interleaved VOB isextracted from the scenario data St7, and the maximum video encode bitrate V₋₋ MRATE from the encode parameters is set based on the interleaveflag VOB₋₋ Fi setting (=1).

At step #1872 the number of interleaved VOB divisions ILV₋₋ DIV isextracted from the scenario data St7.

Step #1876 is the common VOB data setting routine, which is as describedreferring to the flow chart in FIG. 35. Further description thereof isthus omitted here.

The encode parameters of a system stream in which parental lock controlis implemented are thus defined for a VOB Set with multi-scene selectioncontrol enabled as described above.

The process for generating the encode parameters for a system streamcontaining a single scene is described below with reference to FIG. 53.This stream is generated when step #900 in FIG. 34 returns NO, i.e.,when VOB₋₋ Fp=0. The following operation produces the encodinginformation tables shown in FIG. 27 and FIG. 28, and the encodeparameters shown in FIG. 29.

At step #1880, the scenario reproduction sequence (path) contained inthe scenario data St7 is extracted, the VOB Set number VOBS₋₋ NO is set,and the VOB number VOB₋₋ NO is set for one or more VOB in the VOB Sot.

At step #1882 the maximum bit rate ILV₋₋ BR of the interleaved VOB isextracted from the scenario data St7, and the maximum video encode bitrate V₋₋ MRATE from the encode parameters is set based on the interleaveflag VOB₋₋ Fi setting (=1).

Step #1884 is the common VOB data setting routine, which is as describedreferring to the flow chart in FIG. 35. Further description thereof isthus omitted here.

These flow charts for defining the encoding information table and encodeparameters thus generate the parameters for DVD video, audio, and systemstream encoding by the DVD formatter.

Decoder Flow Charts

A. Disk-to-stream buffer transfer flow

The decoding information table produced by the decoding systemcontroller 2300 based on the scenario selection data St51 is describedbelow referring to FIGS. 47 and 48. The decoding information tablecomprises the decoding system table shown in FIG. 47, and the decodingtable shown in FIG. 48.

As shown in FIG. 47, the decoding system table comprises a scenarioinformation register and a cell information register. The scenarioinformation register records the title number and other scenarioreproduction information selected by the user and extracted from thescenario selection data St51. The cell information register extracts andrecords the information required to reproduce the cells constituting theprogram chain PGC based on the user-defined scenario informationextracted into the scenario information register.

More specifically, the scenario information register contains pluralsub-registers, i.e., the angle number ANGLE₋₋ NO₋₋ reg, VTS number VTS₋₋NO₋₋ reg, PGC number VTS₋₋ PGCI₋₋ NO₋₋ reg, audio ID AUDIO₋₋ ID₋₋ reg,sub-picture ID SP₋₋ ID₋₋ reg, and the system clock reference SCR bufferSCR₋₋ buffer.

The angle number ANGLE₋₋ NO₋₋ reg stores which angle is reproduced whenthere are multiple angles in the reproduction program chain PGC.

The VTS number VTS₋₋ NO₋₋ reg records the number of the next VTSreproduced from among the plural VTS on the disk.

The PGC number VTS₋₋ PGCI₋₋ NO₋₋ reg records which of the plural programchains PGC present in the video title set VTS is to be reproduced forparental lock control or other applications.

The audio ID AUDIO₋₋ ID₋₋ reg records which of the plural audio streamsin the VTS are to be reproduced.

The sub-picture ID SP₋₋ ID₋₋ reg records which of the plural sub-picturestreams is to be reproduced when there are plural sub-picture streams inthe VTS.

The system clock reference SCR buffer SCR₋₋ buffer is the buffer fortemporarily storing the system clock reference SCR recorded to the packheader as shown in FIG. 19. As described using FIG. 26, this temporarilystored system clock reference SCR is output to the decoding systemcontroller 2300 as the bitstream control data St63.

The cell information register contains the following sub-registers: thecell block mode CBM₋₋ reg, cell block type CBT₋₋ reg, seamlessreproduction flag SPF₋₋ reg, interleaved allocation flag IAF₋₋ reg, STCresetting flag STCDF, seamless angle change flag SACF₋₋ reg, first cellVOBU start address C₋₋ FVOBU₋₋ SA₋₋ reg, and last cell VOBU startaddress C₋₋ LVOBU₋₋ SA₋₋ reg.

The cell block mode CBM₋₋ reg stores a value indicating whether pluralcells constitute one functional block. If there are not plural cells inone functional block, CBM₋₋ reg stores N₋₋ BLOCK. If plural cellsconstitute one functional block, the value F₋₋ CELL is stored as theCBM₋₋ reg value of the first cell in the block, L₋₋ CELL is stored asthe CBM₋₋ reg value of the last cell in the block, and BLOCK is storedas the CBM₋₋ reg of value all cells between the first and last cells inthe block.

The cell block type CBT₋₋ reg stores a value defining the type of theblock indicated by the cell block mode CBM₋₋ reg. If the cell block is amulti-angle block, A₋₋ BLOCK is stored; if not, N₋₋ BLOCK is stored.

The seamless reproduction flag SPF₋₋ reg stores a value defining whetherthat cell is seamless connected with the cell or cell block reproducedtherebefore. If a seamless connection is specified, SML is stored; if aseamless connection is not specified, NSML is stored.

The interleaved allocation flag IAF₋₋ reg stores a value identifyingwhether the cell exists in a contiguous or interleaved block. If thecell is part of a an interleaved block, ILVB is stored; otherwise N₋₋ILVB is stored.

The STC resetting flag STCDF defines whether the system time clock STCused for synchronization must be reset when the cell is reproduced; whenresetting the system time clock STC is necessary, STC₋₋ RESET is stored;if resetting is not necessary, STC₋₋ NRESET is stored.

The seamless angle change flag SACF₋₋ reg stores a value indicatingwhether a cell in a multi-angle period should be connected seamlessly atan angle change. If the angle change is seamless, the seamless anglechange flag SACF is set to SML; otherwise it is set to NSML.

The first cell VOBU start address C₋₋ FVOBU₋₋ SA₋₋ reg stores the VOBUstart address of the first cell in a block. The value of this address isexpressed as the distance from the logic sector of the first cell in theVTS title VOBS (VTSTT₋₋ VOBS) as measured by and expressed (stored) asthe number of sectors.

The last cell VOBU start address C₋₋ LVOBU₋₋ SA₋₋ reg stores the VOBUstart address of the last cell in the block. The value of this addressis also expressed as the distance from the logic sector of the firstcell in the VTS title VOBS (VTSTT₋₋ VOBS) measured by and expressed(stored) as the number of sectors.

The decoding table shown in FIG. 48 is described below. As shown in FIG.48, the decoding table comprises the following registers: informationregisters for non-seamless multi-angle control, information registersfor seamless multi-angle control, a VOBU information register, andinformation registers for seamless reproduction.

The information registers for non-seamless multi-angle control comprisesub-registers NSML₋₋ AGL₋₋ C1₋₋ DSTA₋₋ reg-NSML₋₋ AGL₋₋ C9₋₋ DSTA₋₋ reg.

NSML₋₋ AGL₋₋ C1₋₋ DSTA₋₋ reg-NSML₋₋ AGL₋₋ C9₋₋ DSTA₋₋ reg record theNMSL₋₋ AGL₋₋ C1₋₋ DSTA-NMSL₋₋ AGL₋₋ C9₋₋ DSTA values in the PCI packetshown in FIG. 20.

The information registers for seamless multi-angle control comprisesub-registers SML₋₋ AGL₋₋ C1₋₋ DSTA₋₋ reg-SML₋₋ AGL₋₋ C9₋₋ DSTA₋₋ reg.

SML₋₋ AGL₋₋ C1₋₋ DSTA₋₋ reg-SML₋₋ AGL₋₋ C9₋₋ DSTA₋₋ reg record the SML₋₋AGL₋₋ C1₋₋ DSTA-SML₋₋ AGL₋₋ C9₋₋ DSTA values in the DSI packet shown inFIG. 20.

The VOBU information register stores the end pack address VOBU₋₋ EA inthe DSI packet shown in FIG. 20.

The information registers for seamless reproduction comprise thefollowing sub-registers: an interleaved unit flag ILVU₋₋ flag₋₋ reg,Unit END flag UNIT₋₋ END₋₋ flag₋₋ reg, Interleaved Unit End AddressILVU₋₋ EA₋₋ reg, Next Interleaved Unit Start Address NT₋₋ ILVU₋₋ SA₋₋reg, the presentation start time of the first video frame in the VOB(Initial Video Frame Presentation Start Time) VOB₋₋ V₋₋ SPTM₋₋ reg, thepresentation end time of the last video frame in the VOB (Final VideoFrame Presentation Termination Time) VOB₋₋ V₋₋ EPTM₋₋ reg, audioreproduction stopping time 1 VOB₋₋ A₋₋ STP₋₋ PTM1₋₋ reg, audioreproduction stopping time 2 VOB₋₋ A₋₋ STP₋₋ PTM1₋₋ reg, audioreproduction stopping period 1 VOB₋₋ A₋₋ GAP₋₋ LEN1₋₋ reg, and audioreproduction stopping period 2 VOB₋₋ A₋₋ GAP₋₋ LEN2₋₋ reg.

The interleaved unit flag ILVU₋₋ flag₋₋ reg stores the value indicatingwhether the video object unit VOBU is in an interleaved block, andstores ILVU if it is, and N₋₋ ILVU if not.

The Unit END flag UNIT₋₋ END₋₋ flag₋₋ reg stores the value indicatingwhether the video object unit VOBU is the last VOBU in the interleavedunit ILVU. Because the interleaved unit ILVU is the data unit forcontinuous reading, the UNIT₋₋ END₋₋ flag₋₋ reg stores END if the VOBUcurrently being read is the last VOBU in the interleaved unit ILVU, andotherwise stores N₋₋ END.

The Interleaved Unit End Address ILVU₋₋ EA₋₋ reg stores the address ofthe last pack in the ILVU to which the VOBU belongs if the VOBU is in aninterleaved block. This address is expressed as the number of sectorsfrom the navigation pack NV of that VOBU.

The Next Interleaved Unit Start Address NT₋₋ ILVU₋₋ SA₋₋ reg stores thestart address of the next interleaved unit ILVU if the VOBU is in aninterleaved block. This address is also expressed as the number ofsectors from the navigation pack NV of that VOBU.

The Initial Video Frame Presentation Start Time register VOB₋₋ V₋₋SPTM₋₋ reg stores the tine at which presentation of the first videoframe in the VOB starts.

The Final Video Frame Presentation Termination Time register VOB₋₋ V₋₋EPTM₋₋ reg stores the time at which presentation of the last video framein the VOB ends.

The audio reproduction stopping time 1 VOB₋₋ A₋₋ STP₋₋ PTM1₋₋ reg storesthe time at which the audio is to be paused to enable resynchronization,and the audio reproduction stopping period 1 VOB₋₋ A₋₋ GAP₋₋ LEN1₋₋ regstores the length of this pause period.

The audio reproduction stopping time 2 VOB₋₋ A₋₋ STP₋₋ PTM2₋₋ reg andaudio reproduction stopping period 2 VOB₋₋ A₋₋ GAP₋₋ LEN2₋₋ reg storethe same values.

The operation of the DVD decoder DCD according to the present inventionas shown in FIG. 26 is described next below with reference to the flowchart in FIG. 49.

At step #310202 it is first determined whether a disk has been inserted.If it has, the procedure moves to step #310204.

At step #310204, the volume file structure VFS (FIG. 21) is read, andthe procedure moves to step #310206.

At step #310206, the video manager VMG (FIG. 21) is read and the videotitle set VTS to be reproduced is extracted. The procedure then moves tostep #310208.

At step #310208, the video title set menu address information VTSM₋₋ C₋₋ADT is extracted from the VTS information VTSI, and the procedure movesto step #310210.

At step #310210 the video title set menu VTSM₋₋ VOBS is read from thedisk based on the video title set menu address information VTSM₋₋ C₋₋ADT, and the title selection menu is presented.

The user is thus able to select the desired title from this menu in step#310212. If the titles include both contiguous titles with nouser-selectable content, and titles containing audio numbers,sub-picture numbers, or multi-angle scene content, the user must alsoenter the desired angle number. Once the user selection is completed,the procedure moves to step #310214.

At step #310214, the VTS₋₋ PGCI#i program chain (PGC) data blockcorresponding to the title number selected by the user is extracted fromthe VTSPGC information table VTS₋₋ PGCIT, and the procedure moves tostep #310216.

Reproduction of the program chain PGC then begins at step #310216. Whenprogram chain PGC reproduction is finished, the decoding process ends.If a separate title is thereafter to be reproduced as determined bymonitoring key entry to the scenario selector, the title menu ispresented again (step #310210).

Program chain reproduction in step #310216 above is described in furtherdetail below referring to FIG. 50. The program chain PGC reproductionroutine consists of steps #31030, #31032, #31034, and #31035 as shown.

At step #31030 the decoding system table shown in FIG. 47 is defined.The angle number ANGLE₋₋ NO₋₋ reg, VTS number VTS₋₋ NO₋₋ reg, PGC numberVTS₋₋ PGCI₋₋ NO₋₋ reg, audio ID AUDIO₋₋ ID₋₋ reg, and sub-picture IDSP₋₋ ID₋₋ reg are set according to the selections made by the user usingthe scenario selector 2100.

Once the PGC to be reproduced is determined, the corresponding cellinformation (PGC information entries C₋₋ PBI#j) is extracted and thecell information register is defined. The sub-registers therein that aredefined are the cell block mode CBM₋₋ reg, cell block type CBT₋₋ reg,seamless reproduction flag SPF₋₋ reg, interleaved allocation flag IAF₋₋reg, STC resetting flag STCDF, seamless angle change flag SACF₋₋ reg,first cell VOBU start address C₋₋ FVOBU₋₋ SA₋₋ reg, and last cell VOBUstart address C₋₋ LVOBU₋₋ SA₋₋ reg.

Once the decoding system table is defined, the process transferring datato the stream buffer (step #31032) and the process decoding the data inthe stream buffer (step #31034) are activated in parallel.

The process transferring data to the stream buffer (step #31032) is theprocess of transferring data from the recording medium M to the streambuffer 2400. This is, therefore, the processing of reading the requireddata from the recording medium M and inputting the data to the streambuffer 2400 according to the user-selected title information and theplayback control information (navigation packs NV) written in thestream.

The routine shown as step #31034 is the process for decoding the datastored to the stream buffer 2400 (FIG. 26), and outputting the decodeddata to the video data output terminal 3600 and audio data outputterminal 3700. Thus, is the process for decoding and reproducing thedata stored to the stream buffer 2400.

Note that step #31032 and step #31034 are executed in parallel.

The processing unit of step #31032 is the cell, and as processing onecell is completed, it is determined in step #31035 whether the completeprogram chain PGC has been processed. If processing the complete programchain PGC is not completed, the decoding system table is defined for thenext cell in step #31030. This loop from step #31030 through step #31035is repeated until the entire program chain PGC is processed.

B. Decoding process in the stream buffer

The process for decoding data in the stream buffer 2400 shown as step#31034 in FIG. 50 is described below referring to FIG. 51. This process(step #31034) comprises steps #31110, #31112, #31114, and #31116.

At step #31110 data is transferred in pack units from the stream buffer2400 to the system decoder 2500 (FIG. 26). The procedure then moves tostep #31112.

At step #31112 the pack data is from the stream buffer 2400 to each ofthe buffers, i.e., the video buffer 2600, sub-picture buffer 2700, andaudio buffer 2800.

At step #31112 the Ids of the user-selected audio and sub-picture data,i.e., the audio ID AUDIO₋₋ ID₋₋ reg and the sub-picture ID SP₋₋ ID₋₋ regstored to the scenario information register shown in FIG. 47, arecompared with the stream ID and sub-stream ID read from the packetheader (FIG. 19), and the matching packets are output to the respectivebuffers. The procedure then moves to step #31114.

The decode timing of the respective decoders (video, sub-picture, andaudio decoders) is controlled in step #31114, i.e., the decodingoperations of the decoders are synchronized, and the procedure moves tostep #31116.

Note that the decoder synchronization process of step #31114 isdescribed below with reference to FIG. 52.

The respective elementary strings are then decoded at step #31116. Thevideo decoder 3801 thus reads and decodes the data from the videobuffer, the sub-picture decoder 3100 reads and decodes the data from thesub-picture buffer, and the audio decoder 3200 reads and decodes thedata from the audio buffer.

This stream buffer data decoding process then terminates when thesedecoding processes are completed.

The decoder synchronization process of step #31114, FIG. 51, isdescribed below with reference to FIG. 52. This processes comprisessteps #31120, #31122, and #31124.

At step #31120 it is determined whether a seamless connection isspecified between the current cell and the preceding cell. If a seamlessconnection, the procedure moves to step #31122, if not, the proceduremoves to step #31124.

A process synchronizing operation for producing seamless connections isexecuted in step #31122, and a process synchronizing operation fornon-seamless connections is executed in step #31124.

Video Encoder

While the material written to the video stream St1 input to the videoencoder 300 in FIG. 25 is a movie or similar content recorded on film,the multimedia bitstream MBS recorded to the digital video disk mediumof the present invention is presumed connected to a consumer televisionreceiver. When encoding a multimedia bitstream, digital VCRs are alsogenerally used to supply material to the authoring encoder shown in FIG.25 because of the ease of editing the video source.

The frame rate of movie film is 24 frames/second, however, while thevideo frame rate of NTSC digital VCRs and consumer televisions is 29.97frames/second. As a result, video materials recorded on film must firstbe converted using frame rate conversion to produce a video signal thatcan be recorded by a digital VCR.

A first embodiment of the reverse frame rate conversion circuit of thepresent invention is therefore described below with reference to FIG.39. FIG. 39 is a block diagram of the video encoder 300A, which differsfrom the video encoder 300 shown in FIG. 25 by incorporating the reverseframe rate conversion circuit of the present invention. The videoencoder 300A thus comprises frame memory 304 and frame memory 306,inter-field difference detector 308, threshold comparator 310, telecinefrequency detector 312, selector 314, and encoder 316.

The input controller 302 is connected to the scenario editor 100 andencoding system controller 200 shown in FIG. 26 from which the videostream St1 and video encoding signal St9 are respectively received. Ifthe video stream St1 is a frame-rate-converted image, the video encodercontrol data carried in the video stream St1 contains informationindicating frame rate conversion.

After frame-rate converted (telecine) image RT1 is delayed one frame bythe frame memory 304, it is input as frame-delayed source image RT2 toframe memory 306, selector 314, and inter-field difference detector 308.

The inter-field difference detector 308 obtains the inter-fielddifference between the same-parity fields in the frame-delayed sourceimage RT2 and the frame-rate converted (telecine) image RT1 input fromthe input controller 302. The result is output as the difference RT3 tothe threshold comparator 310.

The threshold comparator 310 compares the difference RT3 with aparticular threshold value, and inputs the comparator result signal RT5to the telecine frequency detector 312.

The telecine frequency detector 312 internally produces the frequencyinformation RT6 based on the comparator result signal RT5. Then based onthe frequency information RT6, the telecine frequency detector 312generates and outputs the selector control signal RT7 to the selector314, thereby controlling the selector 314 to output an image matchingthe telecine frequency. The telecine frequency detector 312 also outputsfor each frame the repeat first field flag RFF, top field first flagTFF, and output image effect flag IEF to the encoder 316. The repeatfirst field flag RFF indicates whether a redundant field was deleted inthe frame; the top field first flag TFF declares the presentationsequence of the two fields in the frame; and the output image effectflag IEF declares whether the frame input to the encoder 316 is to beencoded.

The frame-delayed source image RT2 output from the frame memory 304 isdelayed another frame by the second frame memory 306, which thusproduces and output to the selector 314 the 2-frame delayed telecineimage RT4.

Based on the frame-delayed source image RT2 input from the frame memory304, the 2-frame delayed telecine image RT4 input from the frame memory306, and the selector control signal RT7 input from the telecinefrequency detector 312, the selector 314 selects the top field andbottom field from the frame-delayed source image RT2 or the 2-framedelayed telecine image RT4 to produce the reverse-telecine image RT8.This reverse-telecine image RT8 is output to the encoder 316.

The encoder 316 then compression encodes the reverse-telecine image RT8input from the selector 314 and the TRR, RFF, and IEF flags input fromthe telecine frequency detector 312.

FIG. 32 shows the film image, the NTSC video signal produced by framerate conversion (telecine conversion) from the film material (thetelecine image), the reverse-telecine image encoded by the video encoder300A comprising the reverse frame rate conversion circuit (thereverse-telecine image), and the reproduction image obtained by decodingthe encoded image (reverse-telecine image) output from the video encoder300A.

The first row in FIG. 32 shows the 24 frame/second film image IF.

The second row shows the frame-rate converted (telecine) image RT1, theNTSC signal obtained from frame-rate converting (telecine converting) ofthe film image IF.

The third row shows the reverse-telecine image RT8 obtained by detectingand deleting the redundant fields during video encoding of theframe-rate converted (telecine) image RT1 shown in row 2 above; therepeat first field flag RFF, a declared parameter of the video encodingoperation; and the top field first flag TFF. The repeat first field flagRFF declares that the first field in the frame on the time-base is usedas one field in the next reproduction frame; and the top field firstflag TFF declares that the first field in the frame on the time-base isthe top field.

The fourth row shows the NTSC signal of the reproduction image IRobtained from video encoding the reverse-telecine image RT8 data in thethird row.

The frame-rate conversion process whereby a film image is converted toan NTSC video signal thus converts the frame rate by inserting aredundant field copied from a same-parity field at a regular period.Because the film image IF is recorded at 24 frames/second, the top fieldF1t of frame F1 is copied, the bottom field F3b of frame F3 is copied,and the four frames from frame F1 to frame F4 are thus converted to thefive frames F'1 to F'5 of the frame-rate converted (telecine) image RT1.

When the frame-rate converted (telecine) image RT1 is compression coded,coding at the video frame rate will result in the copied redundantfields also being coded. This coding method is obviously inefficient.The copied redundant fields are therefore normally detected and deleted,thus reversing the frame-rate conversion operation, before compressioncoding. As a result, the repeat first field flag RFF indicating whethera redundant field was deleted in the frame, and the top field first flagTFF declaring that the first field in the frame on the time-base is thetop field, are also recorded for each frame during the coding process.

Because the film frame rate to video frame rate ratio is not a simpleinteger ratio, a different conversion pattern is normally inserted at aregular interval in the conversion process. As shown in the figure, theframe-rate conversion process used in this example converts four filmframes to five video frames, effectively converting the frame rate from24 frames/second (fps) to 30 fps. A regular conversion process is thusapplied to the frame-rate converted (telecine) image at basically a fiveframe frequency, and the frequency at each frame is the telecinefrequency. The process obtaining the reverse frame-rate converted(telecine) image from the frame-rate converted (telecine) image variesaccording to the telecine frequency.

The operation of the above reverse frame-rate converter 300A isdescribed below with reference to FIG. 42.

The first row in FIG. 42 shows the frame-rate converted (telecine) imageRT1, frame-delayed source image RT2, difference RT3, and 2-frame delayedtelecine image RT4.

The second row shows the output timing of the comparator result signalRT5.

The third row shows the frequency information RT6 of the frame-rateconverted (telecine) image.

The fourth row shows the selector control signal RT7.

The fifth row shows the reverse-telecine image RT8 output.

The sixth row shows the top field first flag TFF, repeat first fieldflag RFF, and the output image effect flag IEF.

With reference to FIGS. 32 and 42, the frequency of tele-cine conversionis described bellow.

In the first period, state 0, conversion starts when input of frame F1and F2 of frame-rate converted (telecine) image RT1 to frame memory 304and 306 is completed. This conversion generates reverse-telecine imageRT8 from fields F1t and F1b of frame-rate converted (telecine) imageframe F1, and sets the top field first flag TFF to 1 (TFF=1). Becausethe top field of frame F2 is the same as F1t, the field is copied whenthe next frame is reproduced, and the repeat first field flag RFF istherefore set to 1 (RFF=1).

At state 1 conversion starts when input of frame F2 and F3 of frame-rateconverted (telecine) image RT1 to frame memory 304 and 306 is completed.This conversion generates reverse-telecine image RT8 from the bottomfield F2b of frame F2 and the top field F2t of frame F3, and sets thetop field first flag TFF to 0 (TFF=0) because the bottom field comesfirst on the time-base. Field copying also does not occur, and therepeat first field flag RFF is therefore set to 0 (RFF=0).

At state 2 conversion starts when input of frame F3 and F4 of frame-rateconverted (telecine) image RT1 to frame memory 304 and 306 is completed.This conversion generates reverse-telecine image RT8 from the bottomfield F3b of frame F3 and the top field F3t of frame F4, and sets thetop field first flag TFF to 0 (TFF=0) because the bottom field comesfirst in the frame on the time-base. Because the bottom field of frameF4' is the same as F3t, the field is copied when the next frame isreproduced, and the repeat first field flag RFF is therefore set to 1(RFF=1).

At state 3 conversion starts when input of frame F4 and F5 of frame-rateconverted (telecine) image RT1 to frame memory 304 and 306 is completed.This conversion generates reverse-telecine image RT8 from field F4t andF4b of frame F5, and sets the top field first flag TFF to 1 (TFF=1)because the top field comes first in the frame on the time-base. Fieldcopying also does not occur, and the repeat first field flag RFF istherefore set to 0 (RFF=0).

At state 4 conversion starts when input of frame F5 of frame-rateconverted (telecine) image RT1 and F1 of the next period image to framememory 304 and 306 is completed. The reverse-telecine image RT8 is notgenerated during this period, however.

The reverse-telecine image RT8 is thus produced by repeating thisprocess from state 0 to state 4, and the image is encoded.

The process of reverse frame-rate converting from the frame-rateconverted (telecine) image RT1 to the reverse-telecine image RT8 isshown in FIG. 32. The difference between contiguous top fields andbottom fields is compared with a predefined threshold value. If thedifference is less than the threshold, the field is determined to havebeen a copied field, and is therefore deleted. The repeat first fieldflag RFF and top field first flag TFF are also set at the same time.

During reproduction these flags are read to easily reproduce theoriginal frame-rate converted (telecine) image as shown by reproductionimage IR. Specifically, because TFF=1 at frame F1 of reverse-telecineimage RT8, the top field F1t of F1 is output first, and then the bottomfield F1b of F1 is output. Because RFF=1, the first field, i.e., F1t, isoutput again.

At frame F2 the TFF=0, the bottom field F2b of F2 is therefore outputfirst, and the top field F2t of F2 is output next. The top field F1toutput the second time and bottom field F2b create a new frame F2'.

At frame F3 TFF=0. The bottom field F3b is therefore output first, thetop field F3t is output second, and because RFF=1, the bottom field F3bis output again.

At frame F4 TFF=1, the top field F4t is therefore output first, andbottom field F4b is output second. As a result, the frame-rate converted(telecine) image RT1 can be reproduced by reading the flags.

Referring to FIG. 42, frame-rate converted (telecine) image RT1 andframe-delayed source image RT2, the output from frame memory 304 in FIG.39, are compared, and because F1t and F1t' in FIG. 32 are copied fields,the threshold comparator 310 outputs HIGH. Because F1b and F2b in FIG.32 are not copied fields, the comparator result signal RT5 output fromthreshold comparator 310 is LOW. At this point, the telecine frequencydetector 312 determines the state of the telecine frequency, which isstate 0 in this case, controls the output selection signal to LOW tooutput F1t and F1b (FIG. 32) in sequence, and simultaneously outputsTFF=1 and RFF=1. Based on the selector control signal RT7, the selector314 selects and outputs the 2-frame delayed telecine image RT4, which isthe output of frame memory 306 (FIG. 39). As a result, F1t and F1b (FIG.32) are output in sequence as reverse-telecine image RT8. At the nextframe, because F1t', F2t, F2b, and F3b shown in FIG. 32 are not copiedfields, the telecine frequency detector 312 moves to the next state 1,and switches selector 314 by means of selector control signal RT7 tooutput F2t and F2b of FIG. 32 in sequence. Because the bottom fieldcomes first in this frame, TFF=0 is output; because the first field isonly displayed once, RFF=0 is output.

The reverse frame-rate converter 300A outputs in the same manner to F4tand F4b of FIG. 32, at which point it stops outputting for one framebecause of the frame rate difference. To declare this rest period, thetelecine frequency detector 312 negates the output image effect flagIEF.

When a reverse frame-rate converted (telecine) image without a pause isrequired, i.e., when the signal is encoded at the frame rate aftertelecine conversion, FIFO memory for frame-rate conversion is used andthis memory is read for encoding at the frame rate after reverseframe-rate conversion.

However, when plural reverse-telecine converted VOB are contiguouslyreproduced, problems occur during seamless information reproduction atthe VOB connections. These problems are briefly described below usingparental lock control by way of example.

Referring to FIG. 40 and FIG. 41, telecine conversion, the encodedimage, and the state of the reproduction image with parental lockcontrol are described. FIG. 40 shows an example of parental lock controlconnections between three video objects VOBa, VOBb, and VOBc.

The first row in FIG. 41 shows the frame-rate converted (telecine) imageRT1 input to the video encoder 300A. Likewise, the second row shows thevideo stream St15 obtained by video encoder 300A encoding thereverse-telecine image RT8 obtained by reverse-telecine converting theframe-rate converted (telecine) image RT1 shown on row 1. Thereverse-telecine converted image is shown in the figure. Row 3 shows thereproduction image IR decoded from the encoded video stream St15.

In this example, VOBa ending at frame F18 of the original telecineimage, VOBb beginning at frame F19 of the original telecine image andending at frame F44, and VOBc beginning at frame F45 of the originaltelecine image, are obtained by reverse-telecine converting andcompression coding the original contiguous frame-rate converted(telecine) image RT1 in row 1, and depending upon the listener, it isnecessary to skip VOBb and seamlessly contiguously reproduce from VOBato VOBc. In this case, because the end of VOBa of the recordedreverse-telecine converted image in row 3 ends with RFF=0 and TFF=0, andthe beginning of VOBc begins with RFF=0 and TFF=1, if these arecontiguously reproduced, the top fields are contiguous at the connectionbetween VOBa and VOBc in row 1 as shown in row 3.

MPEG decoder behavior is not generally guaranteed in such cases. In aDVD player, a field may be inserted or deleted, resulting at best inincoherent image reproduction and at worst in the insertion of acompletely unrelated, and therefore meaningless, field. Even in thebest-case scenario, i.e., incoherent image reproduction, synchronizationwith the audio may be lost. As a result, true seamless reproductioncannot be achieved.

Regarding this problem, when the present invention provides plurallogical recording periods, i.e., VOB, to a single recording medium,telecine conversion is applied so that the RFF and TFF values at thebeginning and end of each VOB are particular values. The method of thistelecine conversion is described in detail below with reference to FIGS.43 and 44, but the concept is described briefly below.

At the VOB start the RFF and TFF flags are fixed to particular values,telecine conversion is begun from a state in which redundant fielddeletion is prohibited, the redundant fields are deleted and the RFF andTFF flag values are output from the point the RFF and TFF flags producedaccording to the detection results of the actual redundant fields reacha particular value, and telecine conversion is applied so that the RFFand TFF flags hold a particular value at the VOB start.

To set the RFF and TFF flags to particular values at each VOB end, ameans is provided for first detecting the position of the redundantfield in the frame-rate converted (telecine) image RT1 corresponding tothe VOB, and producing the RFF and TFF flags according to the result.When telecine conversion and compression coding are actually executed,deletion of the copied redundant fields is stopped in the frame near theVOB end in the frames that are telecine converted so that the RFF andTFF flags at the VOB end are a particular value, and telecine conversionis applied so that the RFF and TFF flags at the VOB end hold aparticular value.

Alternatively, a means for detecting that the end of the frame-rateconverted (telecine) image RT1 corresponding to the VOB is provided, andwhen it is determined that the end of the VOB is near, telecineconversion is applied by limiting redundant field deletion so that theRFF and TFF flags at the VOB end hold a particular value.

By applying telecine conversion by these means, the RFF and TFF flags atthe VOB start and end are adjusted to particular values, and even if VOBare contiguously reproduced, placement of two bottom fields or two topfields in the same frame is eliminated. Therefore, when plural VOB arecontiguously reproduced, seamless reproduction can be achieved at theVOB connections.

Referring to FIG. 45 a different embodiment of the reverse telecineconversion circuit according to the present invention is described. FIG.45 shows the detailed structure of the video encoder 300B shown in FIG.26 but further comprising the reverse telecine conversion circuit of thepresent invention. The video encoder 300B according to the presentembodiment comprises frame memory 304 and 306, inter-field differencedetector 308, threshold comparator 310, telecine frequency detector 312,selector 314, and encoder 316. However, compared with video encoder300A, it also comprises a VOB end detector 318 and redundant fieldremoval controller 322.

The VOB end detector 318 is connected to the scenario editor 100 of theDVD encoder ECD, and receives the time code input synchronized to thevideo stream in video stream St1. The VOB end detector 318 outputs VOBend signal RT9 based on the video encode end time V₋₋ ENDTM (FIG. 29)that is an encoding parameter produced by the encoding system controller200. The VOB end signal RT9 becomes HIGH at least several frames beforethe time code of the VOB end.

In the present embodiment the time code of the last frame in telecinefrequency state 3 in the VOB is set, and the VOB end signal RT9 isoutput when that frame is input. If the time code corresponding to thetelecine frequency is unknown, the VOB end signal RT9 may be output oneperiod, i.e., five frames before, the VOB end time code.

The redundant field removal controller 322 is connected to the VOB enddetector 318 from which it receives the VOB end signal RT9; and isconnected to the telecine frequency detector 312 from which it receivesthe selector control signal RT7, top field first flag TFF, repeat firstfield flag RFF, and output image effect flag IEF. The redundant fieldremoval controller 322, based on the VOB end signal RT9, controls theselector control signal RT7, top field first flag TFF, repeat firstfield flag RFF, and output image effect flag IEF, and outputs a secondselector control signal RT7', second top field first flag TFF', secondrepeat first field flag RFF', and second output image effect flag IEF'.

The selector 314 is connected to the redundant field removal controller322 and receives the second selector control signal RT7'. Likewise, theencoder 316 is connected to the redundant field removal controller 322and receives the second top field first flag TFF', second repeat firstfield flag RFF', and second output image effect flag IEF'.

If the redundant field removal controller 322 detects a TFF=1, RFF=0state after the VOB end signal becomes HIGH, the encoding process iscontrolled thereafter for images before encoding so that frames of theinput frame-rate converted (telecine) image RT1 in a TFF=1, RFF=0 stateare encoded as is. More specifically, TFF'=1, RFF'=0, IEF'=1, and RT7'=1are fixed, and redundant field deletion is thereafter prohibited. Notethat because the change in RT7 and IEF is synchronized to RFF and TFF,it is sufficient to only detect the change in TFF and RFF.

In other words, unlike video encoder 300A, the selector 314 and encoder316 of the video encoder 300B according to the present embodiment canmore precisely control redundant field deletion by detecting the VOB endin video stream St1 by means of the VOB end detector 318 and redundantfield removal controller 322 based on the time code in the video streamSt1 and the video encoding signal St9 containing encode parameters inputfrom the encoding system controller 200. More efficient and moreaccurate reverse telecine conversion can therefore be achieved.

Referring to FIG. 43 and 44, the reverse telecine conversion method ofthe video encoder 300B is described. Rows 1-3 in FIG. 43 and 44 are thesame as the same rows in FIG. 40 and 41 showing the timing of thereverse telecine conversion as described above, and further descriptionis therefore omitted below. However, row 5 shows the VOB end signal RT9.Frame GF1 is the end time of VOBa, frame GF2 is the start time of VOBb,and frame GF3 is the end time of VOBb.

The reverse telecine conversion of frame-rate converted (telecine) imageRT1 is considered first. Note the end of VOBa ending at frame F18 of theoriginal frame-rate converted (telecine) image RT1. Redundant fielddetection is first applied, and it is assumed that a redundant field ispresent. If the frame-rate converted (telecine) image RT1 is directlyreverse telecine converted, RFF' and TFF' as shown in FIGS. 40 and 41will be produced. Because the frame in VOBa that is near the VOB end andcontains TFF'=1 and RFF'=0 is frame F12' in FIGS. 40 and 41, ifredundant field deletion is prohibited in the period shown as frame GF1,VOBa always ending with a bottom field as shown in reproduction image IRof FIGS. 40 and 41 will result.

The beginning of the next VOBb is considered below. At the start ofVOBb, deletion of the actual redundant fields is prohibited, the TFF'=1and RFF'=0 flags are output, and when TFF'=1 and RFF'=0 first occurs asa result of redundant field detection, redundant field deletion isbegun. The period of frame GF2 is the redundant field deletionprohibited period.

At the end of the VOBb, the same process executed at the VOBa end isexecuted. More specifically, for the period indicated by frame GF3,redundant field deletion does not occur.

At the VOBc start the redundant field deletion mode is entered directlybecause originally TFF'=1 and RFF'=0.

When each VOB cell is thus produced, TFF'=1 and RFF'=0 at the VOBa end,VOBb start and end, and VOBc start. Even if VOBa→VOBb→VOBc arecontiguously reproduced, or if VOBa→VOBc is contiguously reproduced,field discontinuity is eliminated, and seamless reproduction can beguaranteed.

Referring to the timing chart in FIG. 46, the operation of the videoencoder 300B according to the second embodiment of a reverse telecineconversion circuit according to the present invention is described indetail. The timing chart of the present embodiment is the timing chartof the video encoder 300A shown in FIG. 42 with the addition of VOB endsignal RT9, second selector control signal RT7', second top field firstflag TFF', second repeat first field flag RFF', and second output imageeffect flag IEF'. The relationship between the original flags and thesecond flags based on the VOB end signal RT9 described with reference toFIG. 43 and 44 is clear.

The case in which the VOB end signal RT9, which is a reverse telecineconverted signal, is input according to the time code at the timing ofF4t in the telecine image input is shown in this figure. The operationuntil the VOB end signal RT9 is input is the same as described usingFIG. 42.

From the state 3 frame where TFF'=1 and RFF'=0 are first output afterthe reverse telecine converted signal RT9 is input, reverse telecineconversion is stopped, and the input telecine image is output directly.As a result, no matter what position encoding is stopped, the cell willend with a frame starting with a top field, and seamless reproductioncan be assured when plural VOB are contiguously reproduced.

Further description of the VOB end detector 318 and redundant fieldremoval controller 322 referring to FIG. 43 and 44. FIG. 45, and FIG. 46is omitted below because those skilled in the art can construct insoftware or hardware a VOB end detector 318 and redundant field removalcontroller 322 capable of performing these operations.

The VOB end is detected by means of a time code in the presentembodiment, but this can also be achieved by counting the frames withthe same effect described above. In addition, the VOB are described asending with TFF'=1 and RFF'=0 states, but other values can also be usedto prevent the occurrence of problems with the telecine frequency at theborders of plural VOB.

A video encoder comprising a reverse telecine conversion circuit asdescribed above corresponds to the video encoder 300 shown in FIG. 26.Based on encode parameters set in step #1800, a subroutine of theencoder flow chart in FIG. 34, specifically the video encode mode V₋₋ENCMD setting (an encode parameter shown in FIG. 29) determining whetherreverse telecine conversion is to be executed, and the video encodestart time V₋₋ STTM and the video encode end time V₋₋ ENDTM, the videoencoding process shown in step #1900 of FIG. 34B is executed.

As described above, even when cells are contiguously reproduced,seamless reproduction can be achieved at the cell borders withoutsuccessive bottom fields or successive top fields being reproduced.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

What is claimed:
 1. A method for generating a bit stream to be stored toa disc, the bit stream containing a video object that contains encodedvideo data and management information, the encoded video data includingone or more video frames, the management information including a firstflag and a second flag for each video frame, the first flag indicatingwhether a first field of a corresponding video frame is a top field or abottom field and the second flag indicating whether the first field ofthe corresponding video frame is presented a plurality of times duringpresentation of the video object, said method comprising:generating theencoded video data from an input video signal, from which at least onefield is removed, and the management information in such a manner thatthe first and second flags have such values that the presentation of thevideo object starts with a top field and ends with a bottom filed; andconverting the encoded video data and the management information to thevideo object.
 2. The bit stream generating method according to claim 1,wherein the encoded video data and the management information aregenerated in such a manner that:a first flag corresponding to a firstvideo frame in the video object is indicative of a first field of thecorresponding video frame being a top field, and a first flagcorresponding to a last video frame in the video object is indicative ofthe first field of the corresponding video frame being a top field, anda second flag corresponding to the last video frame in the video objectis indicative that the first field is not presented a plurality oftimes.
 3. The bit stream generating method according to claim 1, whereinthe encoded video data and the management information are generated insuch a manner that:a first flag corresponding to a first video frame inthe video object is indicative of the first field of the correspondingvideo frame being a top field, and a first flag corresponding to a lastvideo frame in the video object is indicative of the first field of thecorresponding video frame being a bottom field, and a second flagcorresponding to the last video frame in the video object is indicativethat the first field is presented a plurality of times.
 4. An apparatusfor generating a bit stream to be stored to a disc, the bit streamincluding a video object that contains encoded video data and managementinformation, the encoded video data including one or more video frames,the management information including a first flag and a second flag foreach video frame, the first flag indicating whether a first field of acorresponding video frame is a top field or a bottom field while thesecond flag indicates whether the first field of the bottomcorresponding video frame is presented a plurality of times duringpresentation of the video object, said apparatus comprising:a storagemeans for storing an input video signal; a decision means fordetermining at least one removal field to be removed from the storedinput video signal; a video data generating means for removing the atleast one removal field from the input video signal and encoding aremaining part of the input video signal to obtain the encoded videodata; a management information generating means for generating themanagement information including the first and second flags; aconversion means for converting the encoded video data and themanagement information into the video object; and a controller forcontrolling the video data generating means and the managementinformation generating means in such a manner that the first and secondflags in the generated management information have such values that thepresentation of the video object starts with a top field and ends with abottom field.
 5. The bit stream generating apparatus according to claim4, wherein the decision means is operable for comparing adjacent topfields or adjacent bottom fields of the input video signal stored in thestorage means so as to detect at least one redundant field, and fordetermining the at least one redundant field to be the at least oneremoval field.
 6. The bit stream generating apparatus according to claim5, wherein the controller is operable to refer to the managementinformation so as to detect a last removal field that is determined asthe removal field by the decision means and is the bottom field nearestan end of the input video signal, and to control the video datagenerating means to stop any removal of field from the input videosignal after the last removal field is detected.
 7. A machine-readableinformation disc for storing a bit stream containing a plurality ofvideo objects, said information disc comprising:a video object storagearea for storing the video objects containing encoded video data encodedfrom a video signal from which at least one field is removed, andmanagement information therefor; and an index storage area for storingreproduction sequence information indicative of a reproduction order ofthe video objects, and seamless information indicative of at least oneof the video objects that is to be contiguously reproduced; wherein theencoded video data includes one or more video frames, and the managementinformation includes a first flag and a second flag for each videoframe, the first flag indicating whether a first field of acorresponding video frame is a top field or a bottom field, the secondflag indicating whether the first field of the corresponding video frameis presented a plurality of times during video presentation, the firstand second flags having such values that presentation of each videoobject starts with a top field and ends with a bottom field.
 8. Themachine-readable information disc according to claim 7, wherein a firstflag corresponding to a first video frame in the video object isindicative of a first field being a top field, andwherein a first flagcorresponding to a last video frame in a video object is indicative of afirst field being a top field, and a second flag corresponding to thelast video frame of the video object is indicative that said first fieldis not presented a plurality of times.
 9. The machine-readableinformation disc according to claim 7, wherein a first flagcorresponding to a first video frame in the video object is indicativeof a first field being a top field, andwherein a first flagcorresponding to a last video frame in the video object is indicative ofa first field being a bottom field, and a second flag corresponding tothe last video frame of the video object is indicative that said firstfield is presented a plurality of times.
 10. A reproducing apparatus forreproducing an information recording disc as claimed in claim 7, saidreproducing apparatus comprising:an arrangement operable to readinformation recording disc to reproduce the video objects, thereproduction sequence information, and the seamless information; and acontroller operable to control said arrangement such that:thereproduction sequence information, and the seamless information are readout first, the video objects are read out in order according to thereproduction sequence information, and a read out video object, which isspecified as a seamless reproduction video object by the seamlessinformation, is reproduced in a seamless manner with respect to apreceding reproduced video object.
 11. The reproducing apparatusaccording to claim 10, wherein the first flag (TFF) corresponding to thefirst video frame and the last video frame of each video objectindicates that the first field is a top field and that the second flag(RFF) corresponding to the last video frame of each video objectindicates that said first field is not to be presented a plurality oftimes.
 12. The reproducing apparatus according to claim 10, wherein thefirst flag (TFF) corresponding to the first video frame of a videoobject indicates that the first field is a top field, that the firstflag (TFF) corresponding to the last video frame of said video objectindicates that the first field is a bottom field, and that the secondflag (RFF) corresponding to the last video frame of said video objectindicates that said first field is to be presented a plurality of timesduring video presentation.
 13. A reproducing apparatus for reproducingan information recording disc as claimed in claim 7, said reproducingapparatus comprising:a reading means for reading said informationrecording disc to reproduce the video objects, the reproduction sequenceinformation, and the seamless information; and control means forcontrolling said reading means such that:the reproduction sequenceinformation, and the seamless information are read out first, the videoobjects are read out in the order according to the reproduction sequenceinformation, and a read out video object, which is specified as aseamless reproduction video object by the seamless information, isreproduced in a seamless manner with respect to a preceding reproducedvideo object.